District police are investigating allegations that an off-duty D.C. police officer pulled his gun on a driver of a van in a dispute over a parking spot on a busy street in Northwest Washington Thursday night.

Witnesses, many of them diners at sidewalk tables at La Fonda Restaurant at 17th and R streets NW, told police officials that the off-duty officer leaped out of his car and stuck his gun directly in the stomach of the van driver, yelled an obscenity and added, "I'm a cop." After the van driver pulled away, the officer calmly entered a videotape store, they said.

District police identified the off-duty policeman as Officer Michael Wilson, a 16-year member of the D.C. police force assigned to the patrol support section in the 3rd District.

The incident is under investigation, said Capt. William B. Riley, commander of the patrol support section. Wilson was on a regularly scheduled day off yesterday and is not due to report to work until Monday, Riley said. By that time, some decisions will have been made on Wilson's status, he added.

If criminal activity is indicated, the case will be referred to the U.S. attorney's office and then personnel decisions will be made, Riley said.

Wilson could not be reached last night for comment.

Roberto Padilla, the driver of the van, said he owns a tortilla factory and was delivering tortillas to La Fonda when the incident occurred.

"He said, 'I have a gun. I'm a cop.' Before anything, he pulled a gun," Padilla recalled.

Padilla's account was substantiated by several witnesses who became angry when police officers at the scene allowed the officer to drive away.

One of the diners had run to a U.S. Secret Service officer, who was parked across the street when the incident occurred and who then followed the officer into the video store and ordered him to put his hands up.

The D.C. officer, dressed in a business suit and accompanied by a woman, returned to his car as several D.C. police cars arrived and, after showing a badge, drove off, witnesses said. Police said later that Wilson had been ordered to report to the police station.

"It was an abuse of his power as a police officer," said Jared Falek, a witness. "He was on a social, personal task. He used his position -- and his gun -- to threaten and intimidate the van driver and the rest of us." The officer had gone to the video store to return some movies, according to a store employe.

Several witnesses said they planned to write letters of complaint about the incident. Riley said the police department has taken several written statements and talked to witnesses.