An off-duty Philadelphia police officer shot and killed a 21-year-old man in Port Richmond late Saturday night after "a large fight in the street," said Lt. Frank Vanore, police information officer.

"A large crowd formed" around 11 p.m. in the 2600 block of Elkhart Street, Vanore said. About 20 to 30 young people were there, he said. The off-duty officer, whom he declined to name, came out of a nearby residence and tried to control the situation, Vanore said.

When the officer was physically pushed and attacked by several males, he fired his weapon once, hitting William Panas in the chest, Vanore said. Panas was taken to Temple University Hospital, where he was pronounced dead at 11:33 p.m.

No other weapons were discharged, Vanore said, and no one was charged. He said the off-duty officer had been assigned to the Civil Affairs Unit, which handles labor disputes, but will be placed on administrative duty pending an investigation.

The Homicide Unit and the district attorney are both looking into the incident, Vanore said. He said he did not know how long the officer has been with the department.

Contact staff writer Jan Hefler

at 856-779-3224 or jhefler@phillynews.com.