JACKSONVILLE, Fla. -- A man in Jacksonville was seriously burned when he accidentally set off a commercial firework in his car that he apparently intended to throw at his girlfriend, according to a report.

Investigators said the Shannon Kramer, 35, got into an argument with his girlfriend Sunday night on Herschel Street.

Police said he later got into his car, and apparently lit the explosive with the intention of throwing it at his girlfriend, but the device dropped between his legs, WJXT-TV reported.

"He light the fuse, which was long -- they believe about 18 inches -- but it was about a half-second burn time," Jacksonville Sheriff's Office Lt. Larry Gayle said. "He was prepared for the fuse to burn down that fast. He thought he had time to throw the device."

Neighbors who heard the explosion ran to the car, saw the man on fire and used a fire extinguisher to put out the flames.

Kramer suffered burns to his legs and groin, and was taken to Shands-Jacksonville Medical Center.

Jacksonville police said a passenger in the car fled after the blast.

The bomb squad is still investigating, but it's not known if Kramer will be charged with a crime.