An apparent traffic accident that claimed the lives of a man and his two daughters last week is now being investigated as a double murder-suicide.

John Daubs — who was estranged from his wife — and his daughters Ashley, 15, and Stephanie, 12, were killed instantly in a head-on collision with a dump truck-trailer combo on Clarke Road, an 80km-an-hour highway near London, Ont.

The truck driver suffered minor injuries and was released from hospital later that evening.

Police had been checking four major theories on the cause of the collision — accidental, mechanical, medical emergency or intentional — but focused on the latter after speaking with witnesses and examining forensic evidence.

"At this stage, we cannot get into the details. However we do have evidence that would suggest this was an intentional act," London police spokeswoman Const. Amanda Pfeffer told CBC News Online.

The London Free Press, in an interview with the truck driver, said Daubs's car crossed the centre line at the last second and that the truck was on him "in the blink of an eye."

Pfeffer said the investigation was in "a bit of a holding pattern," waiting for results back from the Centre for Forensic Study and medical results from the autopsy.

Debbie Daubs, mother of the girls, has asked for privacy and would not directly comment on the incident. Her daughters are due to be buried Wednesday.