DENVER (REUTERS) - Tens of thousands of people across the US Rockies were left without power on Monday (March 15) and flights were grounded at Colorado's Denver International Airport as the region dug out from one of the most powerful late-winter blizzards in some two decades.

The heavy storm punished parts of Colorado and Wyoming with up to 3 feet of snow and wind gusts of 45 miles per hour over the weekend, stranding motorists on major highways, and knocking down trees and power lines.

"All runways will remain closed until 2pm today - no flights will arrive or depart before that time while crews continue to treat the airfield for ice and snow," Denver International Airport said on Twitter.

A photo showed heavy equipment clearing snow-covered runways at dawn.

"If you're scheduled to fly into or out of DEN today, check your flight status with your airline," the nation's fifth-busiest airport said. Around 2 feet of snow fell at the airport over the weekend.

Airport staff gave blankets and water to the roughly 500 passengers that were left stranded at the airport overnight, the Denver Post reported. At one terminal, employees of a McDonald's restaurant passed out free food, the paper said.

State government offices in Denver and surrounding suburban counties were to remain closed on Monday.

Interstates 70 and 25, two of Colorado's main arteries across the state, were shut down on Sunday afternoon, along with Interstate 80, which runs east-west across Wyoming. Motorists were advised to stay off the roads on Monday.

More snow was expected across the Rockies on Monday evening and into Tuesday, although National Weather Service forecasters expected it to be considerably lighter and wreak less havoc.

The weather system bringing blizzards to the Rockies was also responsible for severe thunderstorms in Texas over the weekend, including reports of multiple tornadoes on Saturday in the Texas Panhandle.