St. Louis (KMOV) -- An off duty St. Louis County police officer shot and killed a person who allegedly tried to steal his car at his home in Florissant around 12:30 p.m. on Sunday, said Florissant Police Chief Bill Karabas.

Karabas said the off duty officer was doing a home improvement project on Claire Dr. near New Florissant Rd. and had just moved his vehicle when two suspects allegedly approached him and demanded his car.

One of the suspects had a gun and pointed it at the officer while demanding the vehicle, according to Karabas.

The officer struggled with one of the 18-year-old suspects. An unknown number of shots were fired and the suspect was shot in the head and killed, said Lt. Tim Lowery of the Florissant Police Department.

Lowery said a second 18-year-old suspect fled the scene on foot and was captured a short time later by police.

The second suspect is being questioned at the Florissant Police Department head quarters.

Police plan to take the information to St. Louis prosecutors on Monday.

Chief Karabas said both 18-year-old suspects are from north St. Louis City and police are trying to determine what lead them to Florissant.

Police said the St. Louis County officer has been with the police department for more than five years. No other information has been released.

An investigation is ongoing.