darren goforth
Deputy Darren Goforth was shot to death by a gunman at a gas station in Houston on Aug. 28, 2015. Goforth is pictured in this undated handout photo provided by the Harris County Sheriff Department. Handout via Reuters

UPDATE 4:45 p.m. EDT: Police said an arrest has been made in the execution-style slaying of a Texas police officer.

Original post:

Houston Mayor Annise Parker has ordered flags to be lowered as the city mourns the death of Texas sheriff's Deputy Darren Goforth. On Friday night, an unidentified gunman had shot and killed the 47-year-old deputy while he was filling up his patrol car at a gas station.

It’s been called an execution -- one where the photographed killer remains on the loose. From footage of the event, the man reportedly had been unprovoked. Goforth had visited the convenience store at a Chevron gas station in Houston and had finished filling up his patrol car when the gunman “literally shot him to death,” Harris County Sheriff Ron Hickman told a press conference conference Friday, NBC News reported.

The killer remained on the loose Saturday. The gunman, described as a “dark-complected male” in his early 20s, was wearing a white T-shirt and red shorts during the killing and reportedly driving a red Ford Ranger.

Texas authorities questioned a “person of interest” early Saturday morning. While the individual cooperated with the department, he did not disclose details that were pertinent in understanding his relationship to the case, NBC reported.

As the Washington Post noted, Goforth was the 23rd officer to be killed on duty in 2015 alone. In comparison to 2014, that number was fewer. However, the event has renewed conversation of “cop-killing” and police violence. In March, the hashtag #BlueLivesMatter began trending on Twitter following the injury of two police officers in Ferguson.

“We’ve heard black lives matter, all lives matter … well, cops’ lives matter, too. So why don’t we just drop the qualifier and just say 'lives matter?’ ” Hickman asked during the press conference, according to Fox News.

That hashtag took off again on Twitter following Goforth’s death. In the past day, more than 4,500 tweets have been sent with #BlueLivesMatter, according to data from social analytics firm Topsy.

Texas Gov. Greg Abbott issued a statement Saturday afternoon with condolences to the officer’s family as well as ensuring these acts will not be tolerated by the state. “Heinous and deliberate crimes against law enforcement will not be tolerated by the state of Texas,” Abbott said in a statement.

“Texas reveres the men and women in law enforcement who put their lives on the line every day to protect and serve their communities. … I know local law enforcement will work tirelessly to apprehend the killer and ensure justice for Deputy Goforth is served.”