Police are working to determine what caused a Bridgton man to violently attack a couple in their home.

Bridgton Police responded just after 8 o'clock Wednesday morning to a 911 call at the home of Robert and Margaret MacDonald. When officers arrived, they found the two 77-year-old residents with serious head injuries.They were taken to a Bridgton hospital for treatment, and Margaret was later transported, via LifeFlight helicopter, to Maine Medical Center in Portland.

37-year-old Michael Holden was taken in for questioning, and then arrested later that afternoon. He's been charged with Elevated Aggravated Assault, Aggravated Assault, Burglary, and Possession of a Scheduled Drug.  Police say Holden lives with his grandfather, about a mile from the MacDonald's home, but the victims didn't know him. Now, Bridgton and State Police are working to determine what motivated the attack.

MacDonald is the co-owner of two car dealerships, MacDonald Motors, in Bridgton and North Conway, New Hampshire.