It was the middle of the night and Barbara Short

The assault continued for 20 minutes, according to Shorter and others who witnessed it earlier this month from at least two low-rise apartment buildings on Shipley Terrace in Southeast Washington. But by the time police arrived, the ruckus was over; the gang had thrown the victim into a car and sped off.

In most cases police respond immediately to reports of serious crimes in progress. According to a 1980 police department study, officers were on the scene of serious emergencies within an average of 2 1/2 to 3 minutes of receiving a call. Yet there are times when, for a variety of reasons, the system fails.

This was apparently one of those times. A teen-age boy, not since located or identified, was brutally beaten for nearly half an hour, according to witnesses. Shorter and another witness, Alma McGhee, both said they called police twice to report the assault soon after it began. Neither left her name or phone number, however, and the police department, which receives hundreds of anonymous reports of "disorderlies" every week, was busy investigating other emergency calls.

The incident is a nagging concern for Shorter and other residents of the Garfield-Douglass Heights community and has left many wondering what happened to "that child," why police did not arrive in time to help and whether it could happen again.

It is also the most recent example of an ongoing conflict between police and citizens over how officers respond to emergency calls. It comes at a time when police are developing a new policy of not sending police officers to investigate every complaint received over 911 or other emergency lines. Police officials say the policy applies to noncritical emergencies such as reports of larcenies and would have no effect on the kind of report Shorter called in during the early morning hours of March 6.

Police said officers were assigned to the Shipley Terrace incident at 3:38 a.m., 17 minutes after the first call was received. Police could not say what time officers arrived on the scene. They did say that the officer involved reported finding no one at the scene 32 minutes after the first call.

In the meantime, police units in the area were working on a rape, burglary, robbery, stolen auto and report of destruction of property, police said. The fight at Shipley Terrace was given a lower priority.

"If someone calls and says it's a fight and hangs up, how would you prioritize it?" asked Inspector William Anastos, who heads the Police Communications division, which received 2 million emergency phones calls last year.

"Do we want a delay to happen? No," he continued, "but since we're dealing with humans, it does."

Mary Ross, a member of the area's Advisory Neighborhood Commission 8B, said "There seems to be a pattern with them not responding and they always rationalize what they didn't do."

Ross said that two years ago the community was upset about police responses to a rash of burglaries but the situation had since improved. "I thought they were taking a different attitude towards us," said Ross, who represents an area where getting rid of boarded-up apartments and gaining more and better housing are major concerns. "They just have a blatant disrespect for this community."

Shorter's observation is simple but profound: "All I know is that I called for help and help didn't come."

The concern about the time it takes and how police respond to emergency calls is not limited to Ross, Shorter or the Garfield-Douglass Heights community. Others have complaints that vary in their degree of seriousness but reflect the concerns of many.

* On July 21, 1981, Doris Noble of Southwest, alarmed when she saw a young woman she knew disappear with a strange man, dialed 911 at least three times before police arrived. When they did, 31 minutes after Noble's first call, according to police records, the woman had walked home after being raped in the backyard of a nearby church.

* On June 3, 1980, Marie Patterson responded to the burglar alarm at the office of a local civic organization in Southeast. As she drove past the office she saw three men removing equipment from it. She drove to the Seventh District Police Station, reported what she had seen and asked for assistance. She drove back to the office where the burglary was still in progress. Patterson said she waited but police did not come. She flagged down a police car she saw in the distance. When they returned other police units were arriving but the suspects and most of the office equipment were gone.

* On March 14, 1982, Roberta Hauver heard a woman scream for help twice somewhere outside her Southwest apartment. Hauver said she called police, left her name and phone number, and waited for officers to arrive or call back. She said they never did.

Last year the District Court of Appeals ruled that police are obligated to protect the general public but not individuals and therefore could not be sued for negligence in connection with their responses to emergency calls. The specific case involved two Mount Pleasant women who called police and waited for them to arrive while a roommate was being assaulted elsewhere in the house. A police officer drove past the house without stopping. Another officer apparently knocked on the door but left when no one answered. Intruders then assaulted the two women.

Most police delays and mix-ups are the result of a combination of circumstances ranging from confusion between the telephone dispatcher and an excited caller to limited personnel and other situations that require police attention.

The 30 police dispatchers assigned to each shift also have to juggle the complaints of pranksters and chronic callers, Anastos said. Some 911 callers waste time needed to handle real emergencies by asking for directions or store closing times.

"Differential Response" is the new approach District police have recently taken to handle calls to emergency lines. It is aimed at reducing crime through better management and community involvement.

Police dispatchers will continue to scrutinize calls but will ask more citizens to report by mail, phone or in person minor crimes, traffic accidents and other noncritical incidents not requiring immediate attention. Police will also make more referrals of specific problems to appropriate government agencies.

In the meantime, police officials insist that they do respond to bona fide emergencies in a timely fashion and that they will continue to do so when the caller clearly indentifies the emergency.

On March 13, an Adams-Morgan woman awakened to find a man trying to open her bedroom window. She ran out of the room and called police, who arrived at her apartment within minutes. That case is an example of the kind of rapid response police say happens more frequently. Still, it is little comfort for Barbara Shorter.

She fears the worst for the young man in the street that night. She said she checks the paper every day for the discovery of an unidentified body.

Because Shorter's calls to the police were anonymous, they could not contact her that night for details to investigate further. Since then, police said, no reports of assault or a missing person in the District or Prince George's County have been made that could be linked to this incident.

"We don't have a complainant, we don't have anything," Seventh District Deputy Chief James Kelly explained.

Shipley Terrace is a place where people say you can always tell when something is happening because the window blinds start moving up and down. Shorter has lived there for four years in a small, second-floor apartment, crowded with the photos of her five children plus nieces and nephews.

"Anything that concerns a child, I can't stand the thought of me standing by. . . . I have teen-agers," sighed Shorter, who still remembers the horror of the teen-ager being beaten in the street. And she hopes that if one of her children is in trouble, someone will call police--and get help immediately.