Boulder Sheriff Joe Pelle said Thursday morning that "the event is far from over."
Many areas have received more than 5 inches of rain in the last 24 hours -- 7 inches in Frederick. Parts of Aurora received 0.4 inches of rain in a just 15 minutes Thursday morning.
The National Weather Service called the situation "extremely dangerous" and recommended evacuations in certain ares. At 2:29 a.m. the weather service reported an "overtopping" dam. Four hundred homes in the area received emergency notification. A series of dams overflowed and one broke, killing one.
Numerous creeks have flooded, and the weather service has reported up to three feet of floodwater in some areas.
Almost all roads to Boulder have been cut off. Streets and roads including Colorado 72 are impassable in many areas. A road collapse sent three vehicles into the water around 6 a.m. Firefighters were able to rescue the drivers, who sustained minor injuries, and secure the vehicles.
The first reported fatality occurred when a structure collapsed. Colorado Springs police conducting flood patrols later discovered a body floating in a creek at about 4:15 a.m.
Most of the Front Range is under flood warning or until 8:30 p.m. Thursday. The heaviest rains are expected to come in the afternoon and evening. Flash flood warnings are in effect in at least six additional counties.