A police officer in San Antonio, Texas, was fatally shot Sunday near the city’s police headquarters during a traffic stop, officials said. The police department posted a photo of a man on its Facebook page saying he may have information on the shooting and is seeking public help to identify the person.

The slain police officer was identified as 50-year-old Detective Benjamin Marconi. The 20-year veteran was pronounced dead at a hospital.

The shooting took place when Marconi was in his police car writing a ticket to a motorist. A driver of a black sedan pulled up behind Marconi’s car, walked up to him and shot him twice in the head, according to police authorities. The suspect then walked back to his sedan and drove away.

The San Antonio Police Department released photos of the black sedan on its Facebook page and described the suspect as a black male in a hoodie, baggy pants and likely facial hair.

San Antonio Police Chief William McManus said the motorist pulled up during the traffic stop does not have connection with the shooter. The officials are yet to establish a motive for the incident.

“We consider this suspect to be extremely dangerous and a clear threat to law enforcement officers and the public,” McManus said at a press briefing, adding that an investigation on the “capital murder case” has been launched.

McManus also likened the incident to the ones in Dallas and Baton Rouge, Louisiana. In July, a gunman killed five police officers during Black Lives Matter protests in the Texas metropolis and only 10 days later three law enforcement officials were killed by another shooter in Baton Rouge. Earlier this month, two police officers were gunned down in separate ambushes in Iowa.

“You never want to see anything like this happen. Unfortunately, like Dallas, like Baton Rouge, it’s happened here now,” the chief said. “It’s always difficult, especially in this day and age where police are being targeted across the country,” he said. “Hopefully, we’ll solve this one real quick.”