[van id=”us/2016/11/20/san-antonio-cop-killed-sandoval-whitfield-nr-sot.cnn”]

The officer was writing a ticket when the suspect pulled up behind him and shot the officer in the head. The suspect then reached into the car and shot again. CNN’s Polo Sandoval reports.

Investigators in San Antonio, Texas, are continuing their search for a gunman who they say killed an officer during a traffic stop over the weekend.

San Antonio Police Detective Benjamin Marconi was shot Sunday in his patrol car outside police headquarters, Chief William McManus said at a news conference.

Marconi, who was 50 years old, spent nearly half his life on the force.

“[When] most families will be celebrating the holidays SAPD will be burying one of its own because of an ultimate act of cowardice by a suspect who will be caught and brought to justice,” McManus said.

That’s when a man pulled up behind him.

The man walked up to the patrol car driver’s side window and shot the officer in the head, McManus said. The man then reached through the open window and shot him a second time, McManus said.

After the shooting, the man returned to his vehicle and drove away.

“We consider the suspect to be extremely dangerous and a clear threat to law enforcement officers and the public,” he said.

McManus likened the shooting to the fatal ambushes of police officers in Dallas, Texas, and Baton Rouge, Louisiana, earlier this year.

Last July, sniper Micah Xavier Johnson killed five officers who attempted to protect activists that were marching in Dallas following the deaths of Alton Sterling and Philando Castile, two black men killed by police this summer. It was the deadliest single incident for US law enforcement since September 11, 2001.

Later that month, Iraq veteran Gavin Long fatally shot three officers in Baton Rouge in an ambush attack.

Police are investigating motive in this case, including a possible connection to a Sunday morning officer-involved shooting in Dallas, McManus said.

“Unfortunately, like Dallas, like Baton Rouge, it’s happened here,” he said.

It wasn’t the only ambush attack on Sunday: A police officer in St. Louis, Missouri, was wounded in an ambush shooting but is expected to survive.

“It’s always difficult, especially in this day and age where police are being targeted across the county,” McManus added.

San Antonio Mayor Ivy R. Taylor condemned the shooting and called for patience while the investigation continues.

“I want to extend my deepest condolences to the family of the officer killed outside police headquarters today as well as to our entire police force,” Taylor said. “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.”

Police have asked the public for their help identifying a man in connection with the shooting. Initially, police described a slim black man in his 20s or 30s with a hoodie and baggie pants as a suspect. Later, police said they were seeking to identify that man in connection with the shooting but didn’t call him a suspect. Additionally, police are looking for a black Mitsubishi Galant with chrome rims and tinted windows.

“Hopefully we’ll solve this one real quick, and if this individual is a danger to more police or anyone else we will try to get him off the street as soon as we can,” McManus said.