State Police are trying to figure out the cause of a head-on crash on the Mount Hope Bridge that killed a 63-year-old man and injured five other people. Troopers say a GMC van collided with a Toyota RAV at about 7 p.m. Saturday on the bridge that spans Mount Hope Bay and connects Portsmouth and Bristol. Police say the crash killed the van’s driver, Paul Matthews of Barrington, and injured a passenger in the van. Four people in the Toyota were also injured. The van passenger and two people in the Toyota remained hospitalized Sunday morning. State Police closed the bridge for nearly three hours because of the accident.