Updated

A state trooper was fatally shot while making a traffic stop early Monday and police set up a manhunt for four suspects, authorities said.

The shooting occurred shortly after 2 a.m. near the Carnegie exit of Interstate 279, just west of Pittsburgh. The trooper's gun was missing, police said.

Investigators were looking for a black 2001 Mercury sedan, and officers from several departments joined in a manhunt in a wooded area near the shooting, authorities said.

WTAE-TV in Pittsburgh showed police escorting someone from the woods and a police car driving away with someone in the back seat, but authorities would not say if any arrests had been made.

Late in the morning, state, city and county police surrounded an apartment building and cordoned off streets in Pittsburgh's South Side neighborhood, about 5 miles from the site of the shooting. Police wouldn't immediately say if that search was related to the shooting.

Authorities identified the dead officer as Cpl. Joseph Pokorney.

The last state trooper shot to death in the line of duty was Joseph J. Sepp Jr., 34, who died in 2002. He was shot in the head after stopping a suspected drunken driver in Ebensburg.