From his post in a steel mesh cage, the guard here Wednesday night in the H dormitory dayroom of the Maryland House of Correction could see only the usual cluster of prisoners around the television set and, above them, the iron-barred windows to the outside.

What the guard did not notice was that at least 17 of the men in the recreation room did not belong there. Nor did he see that, one by one, the population of H dormitory was slipping through a corner window to a rooftop, then scrambling through three chain-link fences and into the nearby forest.

It was only hours later that prison officials here realized that 30 inmates -- including five men convicted of murder -- had used precise timing and one steel blade to pull off the second largest prison break in Maryland history.

The hundreds of state and county police who spent today scouring the thick woods and trails between Washington and Baltimore found that most of the inmates fleeing from the medium security prison were not as crafty as those who planned the break [By early Friday, 21 of the 30 had been recaptured, mostly along the main highways or in their old neighborhoods in Baltimore and Baltimore County.]

"These guys are not very smart," said State Police Trooper Michael Snukis, who helped coordinate the search. "They go back to the same areas and confront the same officers who arrested them before."

Police said that only one prisoner was known to have been involved in a violent incident following the break. Franklin Darby, 34, who was serving 15 years for assault with intent to maim, was arrested in western Baltimore around 6:10 a.m. after he was allegedly involved in an armed robbery.

Of the 9 men who had not been captured by tonight, seven were serving terms for violent crimes, including two convicted murderers and two previously convicted of escape.

After detailing about 60 state troopers, more than 40 county and U.S. Park police officers, a dozen trained dogs and three helicopters to the search effort this morning, state police officials reduced the patrols to about 15 men and one helicopter at 3 p.m.

"I have no idea how long this is going to go on or when I'm going to halt it," said State Police Lt. B. T. Haywood. "It could be midnight, it could be tomorrow or later."

"We've finished the phase where we're going to be getting a lot of sightings," said another trooper. "Now we've basically got to wait for them to come out of their hiding places."

Police conducting the search for the escapees, all of whom were wearing civilian clothing, today were told to stop anyone walking along the Baltimore-Washington Parkway and other major roads and ask for identification. Those who could not produce it were hustled into patrol cars and taken to the prison, where a guard checked their faces against photographs of the escapees.

While the manhunt continued, state officials, union leaders, and prison supervisors debated how the escape scheme had been pulled off, and who was responsible for it.

Leaders of the union representing prison guards in Maryland charged that understaffing of the facility was partly to blame, while some state officials noted that the aging prison dormitories -- built in the 19th century -- were hard to keep secured.

Prison officials conceded that at least two hours passed between the break and the time shortly after midnight when guards discovered the escape route and realized men were missing.

At a press conference in Annapolis, Maryland Gov. Harry Hughes pledged to hire additional guards for the state prison system, and said the escape could speed up consideration of recommendations for improvements and new construction at the Jessup facility and the Maryland Penitentiary in Baltimore.

Prison officials said today however, that a normal number of guards was on duty at the prison Wednesday night -- 50 for a total population of about 1,494 inmates.

The prison, which employs 250 guards in all, is under a court order to reduce its inmate population to 1,274 by next July.

Of the 50 guards on duty at the time of the escape, one was assigned to guard the second floor H dormitory dayroom and make rounds every hour around the remainder of the dorm, which houses 106 inmates.

Wednesday night, according to prison officials inmates began to congregate in the room after the dinner period. From 6:45 until 9:45, a general recreational period allows the prisoners to gather on recreation fields, use the showers or the library, or return to their assigned rooms.

Only residents of the H dormitory are allowed to enter its dayroom, but Wednesday night, assistant warden John R. Byrne said, prisoners from two other dormitories and the prison's cellblock got into the room, possibly by swapping places with H dormitory inmates who were occupied elsewhere on the grounds.

One or more men apparently used a round, flexible steel blade normally used on power tools to saw one of the 12 iron bars and part of a screen in a window at the southeast corner of the room, Byrne said. Officials said that the blade was not the type used in the prison workshop and may have been smuggled in.

Authorities speculated today that the escape began around 8:30 p.m., when the grounds grew dark. For the next 1 1/2 hours before the deadline for inmates to be in their rooms, the escapees climbed through the 2-by-2-foot hole and jumped about four feet down to the roof on an adjoining storeroom. Many probably left while their guard was making his five-minute-long rounds, officials said.

From the storeroom, the men could jump about 15 feet to the ground, where they followed an intricate course over about 250 yards and through holes they clipped in three fences to an exit point in a deserted shop area at the southeast corner of the prison yard.

Some men were too impatient to wait for the hole to be clipped in the third, 14-foot fence, and instead climbed over it, leaving shreds of their clothing on the barbed wire. Today, nearly all the captured inmates were suffering from cuts along their arms and hands, police said.

The course the escaped convicts followed was just out of sight of both armed guards in the area. One guard was posted about 200 yards west of the dayroom window, but was assigned to watch the recreation area at the far end of the grounds. Every night, this guard moves to a position close to the storeroom at 9:45. The inmates obviously were aware of that, and were gone by that time.

There are six guard posts outside the fence along the route the prisoners followed. These posts are never occupied at night, however. Prison officials said that was because the posts overlook the vocational shop area of the prison, which shuts down at 3:15 in the afternoon.

It was not until 10:10 p.m. that prison supervisors first realized something was wrong. The nightly count in the prison cellblock revealed two men were missing. Then, I dorm reported five men gone and J dorm seven.

It was not until 10:40 p.m., according to prison officials, that they reported to police that six or seven inmates might have escaped. And it was not until 12:15, they said, that police were notified that a final count showed 30 men gone.

State police officials offered a slightly different account. They said their records show that the first call from the prison did not come until 11:30 p.m., and that the final report was not received until nearly 1:30 a.m.

"There have been some conflicts and we're looking into it," said State Police Lt. Haywood. "It wasn't until the 1:30 report that we started getting troopers in line."

State officials said the break was the largest in Maryland since April 5, 1959, when 34 juvenile criminals broke out of the Patuxent Institution, also in Jessup.