A D.C. police officer was charged with second-degree murder and placed on administrative leave yesterday following an off-duty incident in which he allegedly argued with another man about a parking space and then shot the man in the head outside a downtown Washington bar.

The officer, Michael Clay, 32, and a 10-year vereran of the force, reportedly shot and killed Charles W. White, 21, of Arlington, after the two quarreled about White's car blocking Clay's exit from a parking space.

White and his friends were trying to retrieve a set of keys locked inside the car when the shooting took place about 3 a.m. yesterday in the 1700 block of G Street NW.

According to one witness to the incident, Thomas Evans, night manager of The Exchange, a Pennsylvania Avenue bar and restaurant popular with George Washington University students. White and three companions had just left the restaurant's G Street door when they discovered their keys were locked inside their car.

They returned for a coat hanger and were trying to force the car door open when Clay came out of another bar and ordered White to "move that car now."

Evans said White told him, "I'll move it when I can."

"I didn't hear what was said after that," Evans, a longtime friend of White, recalled, "because I went to call the police. When I turned around, the doorman was saying, 'He's been shot,' and I looked out in the street and saw Charlie lying there, and this guy standing over him with the gun in his hand."

Evans said there were about 20 witnesses to the incident and that he feared for Clay's safety, "because people were just going wild. One guy was screaming that Charlie hadn't done anything, and why was he lying there with his face shot off.

"They [the crowd] started yelling and hitting on Clay, and I think the police got there just in the nick of time." he said.

White was taken to George Washington University Hospital, where he was pronounced dead.

Clay, an officer assigned to the 1st District station, was arraigned on a charge of second-degree murder yesterday in D.C. Superior Court and released on personal recognizance.

Police, who would not disclose even the exact location of the shooting, issued a statement, saying White was killed by a single blast "fired from a gun held in the hands of" Clay. The gun was identified as Clay's .38-caliber service revolver.

Officials also declined to confirm or deny reports that after the incident, 1st District headquarters was flooded by persons who said they saw the incident and wished to give their own accounts of it.

Clay's attorney, Barry C. Stiller, had no comment on the matter.

White, who was born and reared in Arlington and graduated in 1977 from Washington-Lee High School, was described as a usually easygoing man with a temper that could sometimes be volatile. But, as one man who knew him said, "There wasn't nothing bad enough about him that would get his head blasted off. He was just a kid."

One 1st District officer who asked that his name not be used, described the small, thin and somewhat rumpled-looking officer Clay as "the last guy in the world who'd come to mind when you hear about something like this."

"I didn't want to believe it when I heard it was a police officer who did the shooting," said Nellie Shafer of Woodbridge, whose daughter once dated White. "I have a 10-year-old, and I'm always telling him, 'Go find a policeman if you get in trouble. Now I wonder . . . seems like God don't give you many choices anymore."

A hearing in the case has been scheduled for Feb. 12 in D.C. Superior Court.

The last time a D.C. police officer shot and killed a person while off duty occurred in January 1980, when Sgt. Arnold Nicholson, a chance customer in a convenience store in Southeast Washington, shot a would-be robber during an abortive hold-up attempt.