San Antonio police officer fatally shot while writing ticket

An American flag and a Texas state flag fly at half-staff at San Antonio Police Department headquarters near a sign and flowers left by Lucy Aldaba after Det. Benjamin Marconi was fatally shot Sunday, Nov. 20, 2016, in San Antonio. Marconi was writing out a traffic ticket to a motorist when he was shot to death in his squad car Sunday outside police headquarters by another driver who pulled up from behind, authorities said. (Edward A. Ornelas/The San Antonio Express-News via AP) (The Associated Press)

This undated image released by the San Antonio Police Department shows 20-year police veteran, Det. Benjamin Marconi, 50, who was shot and killed Sunday, Nov. 20, 2016, while on duty in San Antonio, Texas. Marconi was shot to death in his squad car while writing out a traffic ticket. (San Antonio Police Department via AP) (The Associated Press)

Authorities say a San Antonio police officer has been fatally shot while writing a traffic ticket outside of police headquarters.

San Antonio police Chief William McManus said the officer was killed late Sunday morning. He says the suspect has not yet been apprehended and a motive is not known.

McManus says the officer had pulled over a vehicle and while he was inside his vehicle writing a ticket, a vehicle pulled up behind him. He says the driver of that vehicle got out, walked up to the officer's driver-side window and shot the officer in the head.

The officer was pronounced dead at a hospital. He was a 20-year veteran of the police force.

McManus says, "This is everyone's worst nightmare."