SAN ANTONIO (CBSNewYork/CBS News/AP) — A San Antonio, Texas police officer was shot and killed during a traffic stop on Sunday.

San Antonio Police Chief William P. McManus said Sunday that the Detective Benjamin Marconi, 50, was sitting inside his car just outside police headquarters when he was shot and killed.

San Antonio Police Detective Benjamin Marconi

San Antonio Police Detective Benjamin Marconi was shot and killed on Sunday, Nov. 20, 2016. (Credit: San Antonio Police)

“This is everyone’s worst nightmare,” McManus said.

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The officer — beyond the fact that he was a 20-year veteran — has not been identified in the shooting that happened around 11:40 a.m. on Sunday, CBS San Antonio affiliate KENS-TV reported.

McManus said the officer had pulled someone over and was writing them a ticket when a black car pulled up behind the officer and stopped. Police believe the suspect’s vehicle was a black Toyota or Nissan sedan.

The driver then got out, approached the officer, shot the officer once through the window, and then reached into the officer’s car and shot the officer again.

After the shooting, McManus said the driver then got back in his car, and escaped in part by driving through the police headquarters’ parking lot.

The shooting comes on the same day a man was fatally shot by San Antonio police after coming out of an apartment following a seven-hour standoff and pointing a gun at officers.

McManus said the man was fatally shot early Sunday following the standoff that began after the man’s ex-girlfriend called police when he apparently attempted to kidnap her.

San Antonio Mayor Ivy Taylor released a statement regarding the officer, extending her deepest condolences to the family of the officer and the police force.

“This type of crime cannot and will not be tolerated. I ask for the community’s thoughtfulness and patience as the investigation continues and SAPD searches for the suspect,” she said.

McManus said the suspect is a black male around 5 feet 7 inches to 6 feet tall in height, wearing a gray sweatshirt and black baggy pants. The suspect also has a beard, KENS reported.

San Antonio police released an image of the vehicle that was seen leaving the scene, as well as a person of interest who they said may have information in the shooting.

Crime Stoppers in San Antonio is offering a reward of up to $10,000 for information leading to an arrest of the suspect.

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