According to Reuters, four people have been reported missing and 10 others have been reported injured after two boats crashed into each other on the Colorado River in Arizona. According to police reports, the head-on collision of boats caused both vessels to sink. The collision occurred late Saturday near Arizona's border with California. Several people had been rescued by boats nearby. Nine other people have been taken to a hospital with injuries that have not been considered life threatening. Divers have been searching for the missing boaters. Causes of the incident are still unknown.