ORLANDO, Fla. — A Florida Highway Patrol trooper was shot and killed by a stranded motorist on Interstate 95 Wednesday morning, the Associated Press reports.

• Trooper shot, killed in incident on Interstate 95 roadside
• Interstate shut down in both directions in Martin County
• Shooter was killed by passing Riviera Beach cop, AP reports

Trooper Joseph Bullock, 42, was killed along the interstate in Martin County, officials with that Sheriff's Office said.

The AP initially said the shooting happened at a rest stop, but a later update removed that reference, saying it happened on the roadside near Palm City, about a 45-minute drive north of West Palm Beach.

Interstate 95 was shut down in both directions in that area and was expected to be for some time during the investigation.

Bullock was killed just after 10 a.m. Then, the stranded motorist was shot and killed by a passing Riviera Beach police officer, AP said. It's unclear why the Riviera Beach cop showed up there.

The gunman's name has not been released.

Bullock was assigned to Troop L in the Fort Pierce area and had been with FHP for 19 years, the agency said. He was also an Air Force veteran.

"Today, the entire Florida Highway Patrol and FLHSMV family is heartbroken as we mourn the tragic loss of Trooper Joseph Bullock, a nearly 19-year veteran of the Florida Highway Patrol who chose to make selflessly serving and protecting others his life’s work," Florida Highway Safety and Motor Vehicles Executive Director Terry L. Rhodes said in a released statement. "Please keep his family and his team members in your prayers."

Bullock is the 49th trooper to die in the line of duty since the agency was founded 80 years ago. The last trooper to die was Trooper Tracy Vickers, who was killed in Orlando in a crash last year on State Road 408.

Information from the Associated Press was used for this article.