LOS ANGELES, Sept. 2 (Xinhua) -- Four people were missing and nine others were injured after two boats collided Saturday night on the Colorado River between western U.S. states of California and Arizona, authorities said on Sunday.

According to the Mohave County Sheriff's Office in Arizona, the communications center received several 911 calls in reference to a boat crash incident on the Colorado River near the Moabi Regional Park, at approximately 8:00 PM local time on Saturday (0300 GMT on Sunday).

All passengers were ejected into the water after a northbound Hallet craft carring 10 people collided head on with a southbound Sleek Craft boat with six people on board. Both vessels sank later.

Several people were pulled from the water by passing boaters.

"Nine were injured. Two of the those were in critical condition," said Mohave County Sheriff Doug Schuster at a press conference, adding that the accident was under investigation.

Local authorities sent divers to search in the river. And all vessels were asked to keep clear of the area.

Located along the banks of the Colorado River at the California and Arizona state lines, Moabi Regional Park is a resort for water recreation and beautiful scenery.