DENVER (AP) -- A winter weather storm has closed major highways, knocked out power to thousands of customers and raised avalanche dangers across Colorado.

Parts of Interstate 25 that runs north and south near of Denver are closed, along with portions of Interstate 70 west of the Front Range following a slew of traffic accidents that kept authorities and snowplows busy.

Xcel Energy reported more than 500 power outages affecting about 18,000 customers, most in the Denver area.

Transportation Department spokeswoman Stacey Stegman said the storm came in very hard Thursday morning, making it difficult for snowplows to keep up.

I-70 eastbound is closed near Denver and stretches of the interstate are also closed west of Denver and near Vail.

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