Texas police officer fatally shot during traffic stop

A manhunt was underway on Sunday for a gunman who shot and killed a San Antonio police officer sitting in a squad car during a routine traffic stop outside the Texas city's police headquarters, authorities said.

The shooting unfolded when a second vehicle pulled up behind the parked patrol car, San Antonio Police Chief William McManus said. Its driver exited and fired two shots through a window, hitting the officer as he filled out a traffic ticket.

The suspect sped away from the scene in a black car, driving through the parking lot that serves the San Antonio Public Safety Headquarters on the western edge of downtown.

"A person pulled up behind the patrol car in a black vehicle, got out, walked up to the passenger window, fired one round, shooting the officer in the head," McManus told reporters near the scene of the shooting. "He then reached in and fired a second round, shooting him a second time."

McManus said he did not know if the motorist who was pulled over for the traffic violation was connected in any way with the man who shot the officer, a 20-year veteran of the force.

The chief said police were looking for an African-American male wearing a hoodie and black pants, whose image was captured by security cameras.

McManus, who did not identify the slain officer, said officials were searching for a motive, though he referred to the targeted killings of police officers in Texas and Louisiana earlier this year during his press briefing.

"This is everyone's worst nightmare," McManus said. "You never want to see anything like this happen. Unfortunately, like Dallas, like Baton Rouge, it's happened here now."

"Attacks against law enforcement officers will not be tolerated in Texas and must be met with swift justice," said Texas Governor Greg Abbott in a statement.

President-elect Donald Trump, when asked about the events in San Antonio, said the killing was "terrible." During his successful campaign to win the presidency, Trump sought to portray himself as the "law and order candidate," in part reflecting anger among the electorate over the police killings.

In July, five Dallas police officers were killed when a black U.S. military veteran opened fire in a sniper attack during a protest decrying police shootings of black men. Days later, a gunman killed three police officers and wounded four others in Louisiana's capital of Baton Rouge.