British police say that more than 1,000 runners remain unaccounted for after a long-distance mountain race was called off due to heavy rain and flooding.

But Cumbria police say that no one has been officially reported missing. According to organizers, the athletes are experienced mountaineers who likely camped for the night or found other shelter.

The Original Mountain Marathon was called off on Saturday after heavy rain and high winds affected much of the Lake District, about 300 miles north of London. But competitors were scattered across the 50-mile course at the time.

A Royal Air Force helicopter is in the area. A mountain rescue spokesman says his team hasn't been called out for any emergencies on Sunday but remains on standby.

The marathon's Web site said the race was founded in 1968. Teams are "totally self-supporting," and competitors do not carry global positioning systems or cell phones.

Competitors race in pairs and carry their tents, clothing and enough food for 36 hours.

"The ethos of the event is to be totally self-reliant, in the wilds, carrying all equipment, no outside support," the Web site said.

"The event is for experienced fell [large hill] runners and everyone should have been able to cope," said Shane Ohly, who spoke to the BBC after completing the race. He said that if competitors got into difficulty they should be able to get into their tents to ride out any bad weather.

Mark Weir, who manages a mine in the area, said he had sheltered about 300 athletes.

"The weather is absolutely horrendous and it's a scene of chaos up here," he said.

The sleepmonsters.co.uk Web site, which filed reports on the race, said conditions had deteriorated throughout the afternoon.

"It seems likely many of those retiring will have to spend the night in whatever shelter they can find ... and everyone will have to wait until the rain stops and the waters subside," the Web site said.

None of the race organizers were immediately available for comment.

According to local hospitals and rescue services, more than a dozen people were treated for minor injuries and mild hypothermia.