Manhunt underway for suspect who shot and killed father of 16

Missouri resident Steven Combs, 41, had another child on the way, police said.

— -- A manhunt is underway for the unknown assailant who shot and killed a Missouri father of 16 while washing his car in Wellston on Sunday.

Steven Combs, 41, can be seen on surveillance video bent down washing his car in a driveway as the suspect walks by. The suspect, dressed in all black, then turns around and approaches Combs and shoots him as he stands up. Combs was shot six times, according to the North County Police Cooperative.

The suspect walks away from the scene at first, then takes off running, the video shows. Investigators do not know his identity, police said.

Minutes after he was shot, a man walks out to find Combs on the ground. The witness is seen running around the driveway and administering aid to Combs before flagging down a police car as it turns the corner with its siren on.

North County Police Major Steve Runge described Combs' death as a "calculated murder," the St. Louis Post-Dispatch reported.

Combs had another child on the way in addition to his 16 children, police said. A GoFundMe campaign created for Combs by the police cooperative says he left behind a "wonderful loving family."

The funeral procession for Combs will include tow trucks and at least one police car because he was a tow truck driver and friends with some officers, the Post reported.

ABC News' Amanda Maile contributed to this report.