LYONS, Colo.—Rescuers in Lyons are holding their breath because the only bridge into the town to rescue stranded flood victims is beginning to crumble.

Boulder police spokeswoman Kim Kobel said Sunday every time a rescue vehicle goes over the bridge, some of the dirt supporting the bridge falls off.

Kobel said without the bridge, there will be no way to get people out by land and poor visibility expected with a new storm moving in Sunday is expected to ground helicopters helping with rescues. She said there is no estimate on the number of people who stayed or have been left behind since flooding began on Wednesday.