VEHICLE WAS INVOLVED IN A 2 VEHICLE ACCIDENT. EXPLORER WAS REAR ENDED BY A VEHICLE (DODGE DAKOTA PICKUP TRUCK) TRAVELING APPROXIMATELY 55 MPH WHILE EXPLORER WAS AT A STOP, WAITING TO MAKE A LEFT HAND TURN. THE IMPACT WAS SLIGHTLY OFF CENTER TO THE DRIVER SIDE. THE DRIVER SEAT BACK COLLAPSED BACKWARDS CAUSING DRIVER AND REAR PASSENGER TO COLLIDE RESULTING IN LACERATIONS AND HEAD INJURIES TO BOTH.