MOABI REGIONAL PARK, Calif. (AP) - Authorities say four people are missing after two boats crashed on the Colorado River, ejecting more than a dozen people who were on board.

The Mohave County Sheriff's Office said Sunday that a boat carrying 10 people and another vessel with six people on board collided head-on Saturday night on the river that borders California and Arizona. Authorities say both boats sank and passing boaters pulled victims from the water.

One person was found in critical condition and flown to a hospital in Las Vegas. Nine others were taken to local hospitals by ambulance.

Authorities are searching for four people who remain missing. Anita Mortensen, a spokeswoman for the Mohave County Sheriff's Office, says none of the boaters were wearing life vests when the collision occurred.