A 300-foot-long breach in Lake Delhi Dam Saturday sent water spilling downstream and hundreds of people fleeing for safety in eastern Iowa.
David Fink, Lake Delhi dam operation manager, called the breach “a catastrophic release of water.”
"It’s going to have a hell of a lot of velocity,” he told The Des Moines Register.
The dam, which sits on the Maquoketa River about 45 miles north of Cedar Rapids, failed following massive amounts of rain.
The road on top of the dam collapsed around 10:30 a.m., and water gushed over just before 1pm the newspaper reported.
Some media outlets are reporting the water reached the eaves of several homes and businesses in the immediate vicinity. Others report rushing water flooding over railings and onto roads and fields.
Authorities sounded flood warning sirens in nearby Hopkinton, a town of 700 residents, giving them five minutes to flee.
One homeowner told Fox News that all he can do is wait until the water gets to his town.
A flood warning was also announced in Monticello, which has a population of 3,700.
Officials do not know if the entire dam will give way, but residents in low-lying areas have been ordered to leave their homes and avoid the debris-filled water, Fox News reported.
There were no reports of injuries.
NewsCore contributed to this report