The cause of a car accident early this morning in Bend that seriously injured three teens is under investigation.  The Deschutes County Sheriff’s Office says it happened just after one in the morning near a bridge on Skyliners Road and involved a 1997 Honda CRV that rolled over onto it’s top.  Investigators say all three of the 16 year old males were taken to St. Charles Bend with serious injuries.  One of them had to be cut out of the car.  Investigators say they think alcohol may have been a factor.