Lyons Highway 66 a raging river

Lisa Daunhauer

At least four people are dead and as many as 350 people are unaccounted for in the wake of devastating flood waters hitting across Colorado, according to The Coloradoan.

Four deaths have been confirmed already, with a fifth possible, as Larimer County Sheriff's Office tweeted a 60-year-old woman was "missing and presumed dead."

Flood waters are raging across Colorado towns, leaving many stranded as heavy rains have forced water out of rivers and onto the streets.

"There's so much water coming out of the canyon, it has to go somewhere, and unfortunately it's coming into the city," Ashlee Herring, spokeswoman for the Boulder office of Emergency Management, told Reuters.

From Chicago Tribune:

More heavy rain was expected as search-and-rescue teams used boats and helicopters to pull stranded residents to safety as flash flood waters toppled buildings, washed out roads and bridges and inundated farmland.

"Given the destruction, there is a high probability" of more fatalities, Boulder County Sheriff Joe Pelle said at a media briefing.

Incredible photos of the scene show just how bad it has become, leaving many stranded. The situation isn't improving either, with storms possibly bringing in an additional one to three inches of rain over the weekend.

"The things that worry us are what we don't know," Pelle told USA Today. "We don't know how many lives are lost, we don't know about homes lost."