Police were initially searching for four victims, but on Monday morning, they located the body of Christi Lewis, 51, according to the Mohave County Sheriff's Department.
The recreational boats crashed Saturday in Moabi Regional Park as darkness was falling on a rushing river crowded with holiday weekend boaters, making the rescue operation hard.
Two of the missing have been identified by their loved ones as Kirra Drury and Raegan Heitzig.
Three people are still missing after two boats collided on the Colorado River in San Bernardino County, sheriff's department officials said Sunday.
One of the vessels sank and the other was heavily damaged.
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Labor Day Weekend fun turned into a nightmare when a Hallet boat occupied by 10 people and a Sleek Craft boat that carried six passengers collided at Pirate Cove Marina. Some passengers in the boats were thrown into the water upon collision while others jumped.
Passing boaters pulled several people from the water.
Two people were critically injured in the crash and flown to the University Medical Center of Southern Nevada in Las Vegas, officials said. Rescuers had to call off the search for the missing until Sunday morning because it was too risky to put divers in the flowing water after dark.
More than 60 crew members from Arizona and California resumed their search on boats at sunrise Monday, tracking their progress with a computer program that mapped the riverbed.
Cops say the river may be closed intermittently near the crash site as searches continue to take place.
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Sherwin said the depth of the water on the river can range from shallow to 30 feet deep.
"We have four parties unaccounted for and presumed submerged", he said.
No one on the boats was wearing a life vest, Mohave County Sheriff's spokeswoman Anita Mortensen said.
'But I don't want to give them the interpretation that there isn't a remote possibility that they made it to shore'.
Both local authorities and other recreational boat owners searched the area Saturday, but the bodies of the two presumed dead have not yet been recovered.
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Officials remain unsure if alcohol was involved in the crash.