Helicopters were rescuing Nevada residents from rooftops on Saturday after a levee broke, sending 3 feet of frigid water into hundreds of homes and endangering thousands.

Some 3,500 people were being evacuated in 26-degree weather as emergency crews worked to rescue the stranded after a 30-foot section of the levee broke along the Truckee Canal at 4:30 a.m.

"Our street was flooded, water to the edge of our driveway and rising quickly ... there's some cars there, the water's up to the doors," resident Bill Sanchez said.

There were no known injuries as of Saturday afternoon but officials had issued a flash flood warning.

The break might have been started by burrowing rodents, an official said.

Ernie Schank, president of the Truckee-Carson Irrigation District, said the break may have been caused by a rodent burrowing and weakening the canal's earthen bank.

"Evidently it was a rat or a gopher hole. The canal did not overtop the bank," he said.

The irrigation district has a bounty on gophers, said Kate Rutan, an administrative assistant at the district office. "Gophers are terrible for making a hole ... and once (water) finds a weak spot, it will go for it," she said.

Truckee River water flowing into the canal was diverted upstream and water in the canal was receding, Schank said.

"Some folks were standing in their driveways and some were on top of their buildings," said Zip Upham, a spokesman for the Fallon Naval Air Station, which provided two helicopters.

The area had gotten heavy rain on Friday as a storm pummeled the West Coast, raising a threat of mud slides and flooding in California, blacking out thousands of customers and blanketing the Sierra Nevada range with deep snow.

Residents were being taken by 10 school buses to a local shelter, and bulldozers were being brought in to shore up the levee, said Chuck Allen of the Nevada Department of Public Safety.

Six helicopters as well as fire department boats were aiding the rescue effort, Allen told FOX News.

"It was a mess up there last night," he said. "It's so cold here. The snow is about 2 inches in depth and the temperatures are right near the frigid mark both for the rescuers and rescuees."

Kristin Watson, who with her family was evacuated to Fernley High School, said she was alerted to the levee break after a neighbor pounded on her door and said within 10 minutes her backyard was flooded.

The family packed their Jeep and attempted to leave but got stuck when the vehicle became submerged in 4 feet of water, said Watson, whose son has a medical condition.

Fire department personnel rescued the family and brought them to a high school, where about 100 others were seeking shelter and more were arriving via school buses.

Watson said crews had been doing work on the levee over the summer and said it was "amazing" how the farther they got from her house the less water there was.

Upwards of 800 homes were affected and at least 3,500 people were being evacuated, making up 10 percent of the town of Fernley, about 30 miles east of Reno.

Dozens of emergency personnel were responding.

The canal brings water from the Truckee River, starting just east of Reno and running to the farming community of Fallon, about 60 miles away.

In December 1996, flooding from a rupture of an irrigation canal that is part of the Truckee-Carson Irrigation District surrounded about 60 Fernley homes with as much as 2 feet of water.

On Jan. 3, 1997, flooding from the Truckee River swamped motels, casinos and other businesses in Reno and made hundreds of homes uninhabitable.

The Associated Press contributed to this report.