A Washington man was killed last night when he exchanged gunfire with two off-duty Prince George's County police officers and a security guard in the parking lot of Eastover Shopping Center as startled shoppers scurried for cover.

The man, whose identity was withheld pending notification of relatives, had been seen moments before with a pistol stuck in his belt walking through an auto parts store and a grocery in the shopping center in Oxon Hill, police said.

James Chandler, a clerk in the Grand Union grocery, said that "when the shots were fired, people in the store were screaming and ducking. The gunfire sounded like kids tapping on the windows of the store."

Neither the officers and guard who exchanged shots with the man nor any bystanders was injured in the shootout, which occurred about 6:40 p.m.

Police refused to release the names of the officers or the guard involved pending investigation. They still were interviewing witnesses late last night.

The incident began, according to police spokesman Robert Law, when a citizen told the shopping center security guard that the man had a gun. The guard then saw the man, believed to be in his late 30s, enter and leave the auto parts store, Law said.

The man then entered the Grand Union, according to Law, and the guard approached an off-duty county police officer outside the store.

Chandler, the Grand Union clerk, said the man was yelling and cursing in the store. At one point, he said, the man shouted at a store stock clerk: "You gonna do something to me, you gonna do something to me." He said the clerk walked away, and the man, then stood in a grocery line for a few minutes.

As the man left the store, the off-duty police officer, who was in uniform, and the security guard watched him step off the curb and past the officer's parked marked police car, Law said, and the officer ordered the man to halt.

At this point, Law said, the man turned around with a pistol in his hand and fired twice.

One bullet knocked out the driver's side window of the police car and the other went through the grocery store window, Law said.

The officer and the guard returned the fire, Law said, and the man dropped to one knee and continued to fire before getting up and running about 50 feet from the store.

An off-duty plainclothes county police officer who patrols the shopping center headed his car in the direction of the shots, Law said, and the man fired on him, piercing the car's windshield.

The officer got out of the car and returned the gunfire, striking the man, who fell to the ground, Law said.

The area quickly was cordoned off as a crowd gathered.

Police searched for stray bullets, one of which was retrieved from the right tire of a car parked nearby. Another bullet was recovered near the delicatessen in the Grand Union