A uniformed Texas sheriff’s deputy was shot and killed at a gas station Friday night in what police called a bizarre incident.

Harris County Sheriff’s Deputy Darren H. Goforth, 47, had just come out of the convenience store of a Houston Chevron gas station where he had filled his patrol car when a man “walked up behind him and literally shot him to death,” Sheriff Ron Hickman said at a news conference. After Goforth fell to the ground, the suspect stood over him and fired several more times.

“It appears to be an unprovoked execution-style killing of a police officer,” Hickman said.

Witnesses called 911, but emergency response teams were unable to save the deputy.

Police are still searching for the suspect, who they described as a “dark-complected male” in his early 20s wearing a white t-shirt and red shorts. He was reportedly driving a dark red or maroon extended cab Ford Ranger.

“We will hunt this person down and do our best to bring that person to justice,” Hickman said.

Goforth, a 10-year veteran of the Harris County Sheriff’s Office, stopped for gas around 9:30 p.m. ET after having just finished responding to a call about an accident. Hickman said there was no indication that call had anything to do with the killing.

Hickman said it appeared at this time that Goforth may have been targeted simply because he was a law enforcement officer. “It strikes us all at the heart of public service,” he said.

The deputy leaves behind a wife and two children.

“Tonight we lost one of our brothers. This is an extremely difficult time right now for the Harris County Sheriff’s Office,” the department wrote on its Facebook page. “We ask that you continue to give us your prayers and thoughts. Continue praying for this deputy’s family.”