A Florida sheriff says his agency is investigating the fatal shooting of a motorist by a Fort Piece police officer.

St. Lucie County Sheriff Ken Mascara said in a statement that 21-year-old Demarcus Semer was killed following a traffic stop made shortly before midnight Saturday.

Mascara says the motorist tried to flee and ran over the legs of one of two officers who stopped his car. The second officer was partially inside the car and fired his gun, killing him, according to authorities.

Mascara stated that Semer has no prior arrests in St. Lucie County. He didn't state why Semer had been stopped.

Fort Pierce Police Chief Diane Hobley-Burney asked the sheriff's office to coordinate the investigation.

Authorities didn't immediately identify the officers or the race of those involved.