500 people unaccounted for in deadly Colorado floods

"Mother Nature is not cooperating." That was the message on Sunday from frustrated authorities battling even more bad weather in flood-hit Colorado, USA.

Heavy clouds and rain grounded helicopters, slowing the search for the nearly 500 people who remain unaccounted for. Authorities fear as many as six may be dead.

"Mother Nature is not cooperating with us today, and currently we are not flying. But tomorrow if we get that window of opportunity, which is sounds like we might get, we have the horsepower to hit it hard," incident commander Shane Del Grosso told reporters.

Up to 1,000 people are waiting to be evacuated, he said.

In the meantime, authorities are looking for opportunities to get in by ground and planning their next steps. But they are waiting for their break.

According to the Colorado Office of Emergency Management, the floods have destroyed 1,502 residential structures and damaged 17,494.

They have also been blamed for as many as six deaths, counting two people presumed to have been killed.

The four confirmed deaths include a man and a woman, both 19, who were swept away after leaving their car Thursday in Boulder County. Authorities said the woman left the car first, and the man jumped out to try to save her.

Another body was found in a collapsed home in Jamestown in the same county. Rescuers recovered a fourth body on a roadway in Colorado Springs in El Paso County.

Those presumed dead include a 60-year-old woman and an 80-year-old woman, both in Larimer County.

Witnesses saw the younger woman swept away by floodwater that demolished her house. The older woman suffered injuries and was unable to leave her home.

Boulder County alone will need an estimated $150 million to repair 100 to 150 miles of roadway and 20 to 30 bridges, county transportation director George Gerstle said. The repair bill will be "10 to 15 times our annual budget," he said.

A helicopter surveillance mission Saturday carrying Colorado Gov. John Hickenlooper and members of Colorado's congressional delegation was diverted twice to pick up people waving to be rescued.