An off-duty D.C. police officer was in a Southeast Washington barbershop last week when two men burst in, approached a teenager and shot him dead, police said yesterday.

The officer said he dropped to the floor with the others in the shop to avoid gunfire, and told his superiors he did not fire his gun because he feared hitting bystanders, according to a report by WUSA-TV (Channel 9).

Andre Reese Jr., 18, was killed Friday at Troyit's Barber Shop, in the 2400 block of Martin Luther King Jr. Avenue SE. Police said it appeared to be a planned killing.

Police said the officer, reported to be a rookie assigned to the 5th District, did what he could under the circumstances. They would not give his name.

"I'm not going to play armchair quarterback," one police official said. "The officer is alive. He did what he was supposed to do."

Gary Hankins, a local leader of the Fraternal Order of Police, said off-duty officers are required to carry guns and use them, if necessary, in life-threatening emergencies. Hankins said an officer must decide whether the use of force will help or aggravate a situation.

"The first priority has to be the safety of innocent bystanders," Hankins said. "The first thing is, you do nothing that causes further harm . . . . You can't come out with simple rules for these situations."

Hankins said the fact that an off-duty officer witnessed a homicide underscores how common killings have become in the city in recent years. The District has had 444 homicides so far this year. It is a record number for the third straight year.

To help stem the homicide rate, police began operating the Rapid Deployment Unit, a quick-strike squad of about 100 officers. Since its start in October, police said, the unit has arrested 339 people, 199 on felony charges. Four homicide cases have been closed.

Yesterday, police were investigating two shootings that occurred in the afternoon. An unidentified man was found shot in the 1400 block of Columbia Road NW, and later died at Washington Hospital Center.

Another man was found shot in the 900 block of Wahler Place SE. His condition could not be learned last night. Staff writer Eric Charles May contributed to this report.