JACKSONVILLE, Fla. -- Sheriff John Rutherford led officers in a moment of silence Thursday morning in memory of an 18-year veteran of the Jacksonville Sheriff's Office killed in a car accident.

Officer Michael Brandt Hartsfield died after the car he was riding in crashed about 10:30 p.m. Wednesday. Police said the Hartsfield girlfriend was driving.

Dwain Senterfitt, JSO director of investigations, said the eastbound car eastbound went off Fort Caroline Road on a curve.

"For still unknown reasons, (the car) left the roadway, went into the ditch there, hit the concrete culvert, flipped and ended up on the roof in the driveway of a residence," Senterfitt said.

Hartsfield and the driver had to be cut out of the vehicle and both taken to Shands-Jacksonville Medical Center. Hartsfield died; the woman -- Vicki Susan Mullins, 44 -- was in stable condition.

"The car was totally destroyed," a neighbor told Channel 4's Nikki Preede. "There was concern that there might have been someone else (in the car). We searched around the ditches and around our property, looking, but we didn't find anyone else."

Senterfitt said it was a single-vehicle crash and there were no witnesses. Traffic homicide detectives investigating the cause of the crash were waiting to talk to the driver at the hospital.

A Thursday-morning assembly scheduled to celebrate outstanding officers and hand out community awards turned somber as the sheriff and Senterfitt talked about the long-time officer losing his life.

"Obviously, we're saddened losing one of our own," Senterfitt said. "Brant has been here 18 years and spent the entire time in Zone 2, in the Arlington area, for those out there."

At a similar ceremony last summer, Hartsfield received a lifesaving award for pulling the victim of a crash from a burning motorcycle.

Funeral services for the 50-year-old officer have not been arranged, but neighbors and friends will hold a candlelight vigil in his memory at 9 p.m. Wednesday outside his home at 11891 Arbor Lake Drive.