At least one suspect is thought to be on the run after eight people died in what police are calling "execution-style killings" at four locations in the US state of Ohio.

It's understood the victims were all related. 

Among those shot in the head were a mother, who was sleeping with her 4-day-old baby next to her, and a 16 year-old boy. Three children survived the attcks.

A manhunt's underway for the killer.

Local sheriff Charles Reader says officers are shocked at the savagery of the killings: