PHOENIX — An earthen dam weakened by heavy rains broke near the Grand Canyon early today, flooding a tribal town and forcing officials to pluck hundreds of residents and campers from the gorge by helicopter. No injuries were immediately reported.

The failure of the Redlands Dam caused some flooding in the village of Supai, where about 400 members of the Havasupai tribe live, a Grand Canyon National Park spokeswoman, Maureen Oltrogge, said.

Heavy rain caused trouble even before the dam burst. A private boating party of 16 people was stranded on a ledge at the confluence of Havasu Creek and the Colorado River last night after flood waters carried their rafts away, Ms. Oltrogge said.

The boaters were found uninjured and were being rescued from the canyon, whose floor is unreachable in many places except by helicopter.

Rescuers were trying to find visitors staying at the Supai Campground and escort them to safety, Ms. Oltrogge said.

Evacuees were being flown to a parking area 8 miles from Supai and bused to a Red Cross shelter in Peach Springs, about 60 miles southwest of Supai, the spokeswoman said.

A flash flood warning was in effect for the area until the early evening, and the National Weather Service in Flagstaff warned that more rain was possible.

Supai is on Havasu Creek about 30 miles northwest of Grand Canyon Village, a popular tourist area on the canyon’s south rim. The creek feeds the Colorado, which runs the length of the canyon.

The helicopters lifting residents out were from the National Park Service, the National Guard and the Arizona Department of Public Safety, Oltrogge said.

In 2001, flooding near Supai swept a 2-year-old boy and his parents to their deaths while they were hiking.

The Grand Canyon, usually packed with visitors during the summer, has been the traditional home of the Havasupai for centuries.