Police said Monday they are treating the deaths of a Virginia man and his twin three-year-old daughters as a murder-suicide.

The bodies of 40-year-old Robert King and three-year-old Caroline and Madison King were discovered Saturday afternoon in King's Mechanicsville, Va., home, WRIC-TV reported.

In a press release Monday, the Hanover County Sheriff's Department said they all had died from either lacerations to their necks or carbon monoxide poisoning, or a combination of those factors.

The two girls lived with their mother, Kristina Hooper, who found the bodies Saturday. Hooper told WRIC she and King had recently separated and were fighting over custody of their twins.

She went to King's home to check on them after he did not answer his phone. When she arrived, she found a van parked against the door of the house and a tube running from the exhaust pipe to the bedroom.

A vigil for Caroline and Madison was scheduled for Tuesday evening in Mechanicsville.