An Arnold, MO, police officer sustained life-threatening injuries after being shot by a suspect he was transporting to booking Tuesday, according to police.

Authorities say the officer was transporting the suspect, reportedly in custody for an alleged burglary, when he was shot by the suspect inside his patrol SUV, reports KMOV.

The shooting happened in the parking lot behind the Arnold Police Department around 2 p.m., and responding officers discovered both men inside the vehicle. Officer Ryan O’Conner was shot once in the head/neck area.

The suspect, 29-year-old Chad Klahs, has died from what police believe was a self-inflicted gunshot wound, reports the Associated Press.

Jefferson County Sheriff’s Capt. Gary Higginbotham says police were unaware that the suspect had a gun that was apparently stolen from a vehicle.