iStock/Thinkstock(SAN BERNADINO, Ca.) — At least one person is missing and 13 were injured after two private boats collided on the Colorado River in southeast California on Saturday night.One person was airlifted to University Medical Center of Southern Nevada with life-threatening injuries, the San Bernardino County Fire Department said. Six were treated for moderate injuries and six were treated for minor injuries.San Bernardino Fire said either one or two people were still unaccounted for, and “presumed submerged.” The two vessels collided head on at about 8 p.m. local time at Pirate Cove Marina in Needles, California, near Moabi Regional Park, a recreational area on the Colorado River, which forms the boundary between California and Arizona. The southern tip of Nevada is about 30 miles north of the park.One of the boats sank while the other sustained heavy damage, officials said. Officials called off the search for missing survivors around 9 p.m.The accident happened after sunset, making rescuing those who fell overboard difficult, authorities said. Some people were found as much as a mile down river due to the rapidly moving water.Officials were unsure if alcohol was involved or the ages or genders of those who were injured.Copyright © 2018, ABC Radio. All rights reserved.