PEACH SPRINGS, Arizona (CNN) -- A group of boaters was forced to scramble to the safety of a rocky ledge after waters from a bursting Grand Canyon dam surged, one of the rafters told CNN on Monday.
Cedar Henning and the other 15 stranded boaters with him were rescued and airlifted out of the canyon by helicopters Sunday. Rescue workers were still searching Monday for 11 people unaccounted for, officials said.
About 270 people had been rescued from the area Sunday and Monday, said Maureen Oltrogge, Grand Canyon National Park spokeswoman.
Henning described the rush of water leading to the breach and subsequent falling rocks as "kind of [like] a freight train moving through." Watch the chopper evacuations »
When the floodwaters surged, the boaters quickly moved to a safer area after their boat, which was tied up, was blown away and flung down the river, Henning said.
"We clambered up to the high ground and waited for it to go by and tried to collect our people," he said. "[We] made it down to where we thought our boats would be, and they weren't there."
Henning said the group stayed at the junction of the Havasu Creek and Colorado River on Saturday night and gathered their food and collected rain in a bottle as a precaution. See where the flooding occurred »
But the group was never scared, Henning said. They knew that other boats would pass and see the group stranded on a ledge, he said.
Henning said his group is fine and there were no other injuries besides a hurt toe.
Oltrogge said many residents in the area have decided not to evacuate. These people were not in any immediate danger, she said. iReport.com: Are you there? Send photos, videos
The problems began after water breached Redland Dam and poured into Cataract Canyon and Supai Canyon, which was heavily flooded, said Gerry Blair, spokesman for the Coconino County Sheriff's Office.
Rescuers used five helicopters -- three of them Black Hawks -- in Sunday's rescue mission. Evacuees were taken to a Red Cross shelter at Hualapai Tribal Gymnasium in Peach Springs.
Blair said visitors who hike down into the canyon are required to register with authorities. Authorities have accounted for most people in the area.
Tourism is the main source of revenue for the Havasupai reservation, which was created in 1882.
Geoff Gourley, a longtime river guide at the Grand Canyon, said that campers on multi-day paddling trips often park their boats at the narrow mouth of Havasu Creek to hike along scenic ridges of the side canyon.
He said heavy rains from as far as 15 miles away can wash into the Havasu, swelling it enough to flush the boats down the river.
"I imagine that's what happened here," Gourley said.