The public rarely sees an emergency situation while it is developing, the way police do. From the first frantic phone call, they must piece together what is happening. They may not grasp the full story for vital minutes. In that time, they scramble to understand exactly what is going on and how they can control it.

Now a new technique enables police to slow an ongoing event, giving them and everyone else time to think. The most spectacular local use of this technique in recent months was at the shocking "IBM shootings," in which two persons were killed and seven wounded.

"There's a guy in the IBM building with a gun!"

Phones jumped at Montgomery County police headquarters: A masked man had plowed his car through the glass doors at IBM near Montgomery Mall, sprayed the lobby with bullets. Bodies all over the floor. And 600 people still in the building.

A few years ago, the cops would have stormed the place and gunned the guy down. Like a western. Unlike a western, they might have shot some bystanders, too.

Not any more. Now they call in the negotiating team.

On their own initiative, the first officers on the scene that May morning sealed off the building from the neighborhood, set up outer and inner perimeters and took up posts there. (Perimeters: From the outside, no one could get in, not a blundering shopper, not an ambitious reporter. Inside, nothing moved: The gunman could see no police cars, no flashing lights, no plastic-fronted SWAT marksmen creeping into position to rush him.) Officers calmly set up headquarters at the nearby Marriott building, even marked out a staging area for the media. One man hurried over to nearby Walter Johnson High to make sure students were kept in for the lunch hour. With surgical finesse, the danger zone was isolated.

It was time for the negotiator, the fulcrum in this tensely balanced situation, the police point man who stays in contact with the suspect as long as it takes, backed up by a superior, the coach, who is part assistant, part adviser.

He got on the phone -- by now, an hour into the siege, police had located the gunman's room -- and talked. For nearly seven hours, he talked -- and listened. At the end, the gunman walked out by himself, leaving behind his four weapons.

"Time is on our side," said Lt. James O'Connell, who commands the negotiators of the Emergency Response Team (ERT) for Montgomery County police. "The patrolmen have learned that it works, and now, instead of kicking the door in, they call for the team."

Since it started in December 1979, the team has never fired a shot nor lost a hostage. Talking It Out

A short course in negotiating with terrorists, suicides and crazies.

How it looks from the negotiator's seat:

* "You have your coach with you all the time, alone in the room with you so you won't have a dozen people yammering at you. He's the monitor. He gets the background stuff from outside and relays it to you. Because you're concentrating every minute on that phone."

* "You don't lie. You don't say, 'We won't arrest you.' You tell your honest feelings. You say, 'Yeah, I understand, I understand,' but you don't have to perjure yourself. Remember, he expects you to try and trick him. If he says he wants a 747 in the parking lot and a free trip to Brazil and you say, 'Sure, okay' . . . well, he knows you gotta be lying."

* "You watch for trigger words. You never talk about killing or shooting. You never say, 'How many hostages you got in there?' because maybe he hadn't thought of that, maybe there aren't any people in there at all."

* "Ask him what his problem is, let him vent. The longer it goes on, the safer everyone is. You really get involved with him, and that's one of the reasons you need a monitor, so you don't go too far and promise him stuff."

* "You always trade off with him. Reduce him to a position of bargaining. If he asks for cigarettes, you trade him three cigarettes for three shells. One time a guy demanded a hoagie and two beers, so we traded for three hostages. We don't normally hand out alcohol, but that time . . ."

* "The negotiator doesn't make any decisions himself. That's why it's never anyone above a sergeant. A demand is always referred to the team manager -- there's always an on-scene manager who's at least a captain -- to give more time and so the guy can't demand action on the spot like he could if you were the chief. He talks to nobody but you."

* "Sometimes the wrong negotiator is put on. You get someone who says, 'I won't talk to anybody but a woman.' We have a woman negotiator now, by the way. You have to be very careful when you change negotiators so the guy won't think you're abandoning him or pulling some trick. You've built a relationship with him, after all." A New Kind of Cop

The man talking is officer Michael Clinton, a negotiator who normally works out of the Germantown station. He likes to say he specializes in up-county rednecks because he comes from Pittsburgh, roots for the Steelers and chews Beechnut tobacco. (Once he was riding the phone in a crisis situation, and it went on so long that his coach had to send out for more Beechnut.)

Clinton has been with the county force eight years, is 31 years old ("I look 55; it ages you") and got into this work because the concept of negotiating intrigued him.

"All those TV shows, like 'The Untouchables,' there was always an ultimatum. They'd bust down the door and get the guy, and the bystanders were never hurt. But every situation is different, and it changes rapidly. The guy may be holding out for something, and suddenly he wants something else. You have to be flexible."

The point is, he says, that the person holed up in there with a gun and a bunch of people is just as anxious to talk as you are. But once you try violence, whether tear gas or a full-scale assault, you have used your options. You can't go back. So first, while you can, you talk.

"If it doesn't work and he panics and does something and gets killed, well . . ." He holds out his hands. "But you tried."

The force's longest session lasted 14 hours. A woman was barricaded in a house. No guns involved. In the end, the police simply walked away and the situation quieted by itself.

"Remember this," Clinton says, "you may have a couple of seconds to make a decision that will take the Supreme Court three years to decide if it was right." No More Munichs

The idea started with a Lt. Frank Bowles of the New York police in the wake of the 1972 Munich Olympics massacre. Baltimore County and others picked up on it, and Montgomery County's team trained with Baltimore's, and now police all over the country have ERTs. There are three elements: negotiators, an armed SWAT team and a command group. In addition, a communications unit whose role is growing in importance as various jurisdictions enter the picture: other police departments, rescue squads, hospitals, the FBI and so on. The IBM incident involved 300 emergency personnel.

All this is a long way from the old-fashioned American cop of song and story, who tended to be a more or less rigid personality committed to enforcing not only the law but also the personal code he learned from his daddy. Negotiators are picked carefully through psychological tests. They tend to be extroverts, sociable people, natural salesmen, patient and generally laid back. They can be patrolmen, juvenile officers, investigators, whatever. Most are college graduates, and not a few have master's degrees.

Montgomery has a director of stress management, Virginia Pendergrass, a psychologist who has been with the force a year. She counsels the whole department on stress problems. And no matter how balanced a personality the negotiator is, there is stress. Six hours on the phone can wear anybody down.

"We train every month," Lt. O'Connell said. "We've sat in at the county crisis center, and we have seminars and exercises. One time we had an all-day exercise at Shady Grove and a high police official wandered onto the scene and said, 'What's going on?' So we said, 'Well sir, there's a mythical guy in there holding mythical hostages. And you're in charge.' It was good practice for him."

There are 16 negotiators now, working in three shifts through the month on a 24-hour basis. Incidents usually start in the night, and it's a matter of luck who will be the one on the phone, at least in the beginning. One of O'Connell's jobs is to match negotiator and subject.

"The main problems," he said, "are good intelligence, establishing communication and press cooperation." This means: knowing as much as you can about the subject (His wife comes up and offers to talk to him, but is she the reason he's there? Will he blow everybody up at the sound of her voice?); getting him to the phone (Suppose he's ripped it off the wall?); trying to keep the media from becoming part of the problem (What if a reporter gets through to him independently and asks if he's killed any hostages? And he hadn't even thought of those people as hostages?)

The negotiators work regularly with the armed SWAT teams. The SWAT people know what to expect from them, and the negotiators have confidence they will be ably backed "when we're rapping on a door and there's someone with a gun inside and we have no gun."

There have been times, in fact, when a subject has left a door open carelessly and the SWAT team has rushed in to end the crisis abruptly. The Transgressors

Talking among themselves, police put these cases into three categories: "criminals, crazies and crusaders." Criminals are the easiest because they want to get away (and so are already vulnerable), are accustomed to dealing with police and, in a couple of words, are fairly predictable. Mentally disturbed people usually want help, whatever their wild demands at first. Many are would-be suicides, and the teams have learned that if they can talk these people through their period of depression -- "They can't see the solution even if it's right there in front of them; you show them alternatives, you show them you're concerned" -- the situation often solves itself.

"We've had no recidivism on suicides, no one who tried it again," O'Connell said. "Maybe just knowing someone cares is enough."

The crusaders are toughest. "These are your terrorists. We haven't had one here, but we're prepared for it. They're not afraid to die, which gives them an advantage. The problem is to identify 'em. It may be a bank robber on the phone who's posing as a terrorist. This is where you need all the intelligence you can get. You have research people who can fill you in on the buzzwords."

The work of the ERT is increasing steadily. Montgomery County had 10 cases in 1980, 10 in 1981 and another 10 so far this year. Nobody has ever been able to work up a profile of the typical hostage holder, but police have learned a few things: Don't put a minister on the line or a psychiatrist or a family member unless you are certain it will not backfire. At IBM, for instance, the gunman quit when his wife entered the building and talked to him. "All he wanted was for his wife to hear his voice," said Montgomery police chief Bernard Crooke.

O'Connell speculated that the increase in hostage cases and other crises in which private troubles affect the public may have to do with the recession and hard times. Also, there seems to be a rise in child kidnapings among broken families. A veteran policeman himself, with 16 years on the force (both his grandfathers were D.C. police officers), O'Connell answered the first call for volunteers in 1979.

"It all started with the Blair Plaza Citizens Bank holdup in '77," he said. A gunman had kept seven hostages for seven hours, fired more than 200 shots, threatened to kill people if police didn't back off. The 50-odd police and FBI, massed outside with their shotguns and shields and traditional paraphernalia, could see him through the window with a gun in the ear of a hostage.

They backed off. They got him on the phone, had him talk to a friend in Florida. Finally he surrendered. No one was hurt.

O'Connell said, "We realized then that the technique worked."