COLORADO -- Massive floods are still wreaking havoc in Colorado. The high water levels are leaving entire towns sealed off from rescue teams.

Estes Park is without cell phone service and residents there are trapped by flood water.

Parts of Boulder and Colorado Springs are also under water.

National Guard troops have been able to reach the Colorado community of Lyons, among the towns that had been isolated by flooding and left without power and telephone service.

Thousands of additional residents were told to head for higher ground overnight, as the flood threat continues.

The rain that has hung over the region all week is still falling.

The floodwaters have been deadly. Three people have been killed, and with 20 people missing, it's feared that number will grow.