Carbon Monoxide Kills Family of Four in Penn.

Car left running in garage; not clear if it was by accident.

Carbon monoxide apparently killed a married couple and their two children in an eastern Pennsylvania home where police found a car running in the garage, stunning friends and neighbors who recalled the family Tuesday as happy and outgoing.

It wasn't clear whether the car was left running accidentally, or whether it was an intentional act. State police declined to comment on the investigation.

Police were called to the home in Milford Township, Bucks County, at 11:20 p.m. Monday.