May 25—Two men were in a car that struck a tree in northern Frederick County on Wednesday night, then caught fire, apparently causing ammunition inside to explode, Maryland State Police said.

A woman who was driving by stopped to help the men get away from the fire scene. When the woman stopped a short distance away, the men got out and ran, police said.

One occupant of the car had a laceration on his head, a witness reported, Sgt. Josh Bonneville said in a phone interview Thursday.

The man was driving a 2002 Pontiac, Sgt. Freysz, who declined to give his first name, said in a phone interview.

Freysz did not identify the driver, but said police had an idea of who it was.

He said police were dispatched at about 10:04 p.m. Wednesday to Md. 77, just east of Tower Road.

The person who called 911 was a woman driving by, Freysz said.

"Apparently, the car caught fire as she was pulling up to it," he said.

Freysz said the two men got into the woman's car to get away from the burning vehicle. She drove the men a short distance away from the vehicle.

After they left her car, they ran away, Freysz said.

The burning car had ammunition inside, he said.

Police do not think there were any firearms in the vehicle.

At some point after the crash, the ammunition in the car began "cooking off," or exploding due to high temperatures, Freysz said.

Police do not know why the car struck the tree, he said.

Police searched for the driver Wednesday night with a K-9 unit, but did not find him.