(CNN) -- A massive tornado tore into the northern Colorado town of Windsor and nearby towns Thursday, killing one person and damaging many homes and businesses, the town's mayor said.

The storm struck the town of Windsor and "several other areas" of Weld County, a fire spokeswoman says. more photos »

"It will be a long time before the town recovers from this," Windsor Mayor John Vasquez said.

The funnel cloud, accompanied by golf-ball sized hail, blackened the skies over Windsor as it knocked down power lines, shredded crops in fields outside the city and blasted whole neighborhoods.

The southeast side of town was hit the worst by the storm, which began around noon, Vasquez said.

Windsor, with a population of nearly 19,000, is about 80 miles (130 km) north of Denver.

Colorado Gov. Bill Ritter ordered the National Guard to aid rescue and cleanup efforts. He visited the town Thursday evening, saying the number of homes damaged was significant.

"There are places where it looks like the entire roof is missing and places where the wall and part of the roof is missing," he said. iReport.com: Are you there? Send photos, videos

More than 100 children escaped injury when the staff at Windmill Child Enrichment Center hustled them into an interior room as the storm approached, Kristi Bernhardt, the center's director, told CNN. Daycare worker describes huddling with dozens of children »

Rough weather also affected communities in western Colorado. Rising waters prompted authorities to close a 12-mile stretch of I-70 near Grand Junction a few hours after the tornado struck Windsor, about 220 miles away.

Power was out across town, and about 100 people were taking shelter at a local recreation center, he said.

Vasquez said firefighters and utility crews were working to cap ruptured gas lines.

The single fatality reported was at a campground at a park outside Windsor, near the city of Greeley, he said. Authorities had no count of injuries.

Earlier, Weld County Sheriff's Cmdr. Ken Poncelow said more than 100 homes could be damaged. Watch an enormous funnel cloud move in quickly »

"Some are completely demolished and unrecognizable -- just masses of timber," said Scott Scofield, a Weld County deputy.

CNN confirmed that another tornado touched down in Laramie, Wyoming, hitting a high school, a middle school, a Wal-Mart store and houses.

In Fort Collins, Colorado, the Larimer County Sheriff's Office had several reports of damage, including one home destroyed and another in which residents were trapped by a fallen tree, spokesman Don Nadow said.

Witnesses also reported funnel clouds over parts of Loveland, about 13 miles south of Fort Collins, he said.

Several power outages were reported because of downed power lines, but there were no reports of injuries in Larimer County, said Capt. Steve Fleming of the Poudre Fire Authority.

Inspector Dan Engelhardt, a Loveland Fire Department spokesman, said multiple funnel clouds had been reported in that area and several touched down. Loveland and other area fire departments have contributed engine companies and rescue teams to Windsor, he said.

Windsor, Fort Collins and Loveland lie in the shadow of the Rocky Mountains, where the Great Plains give way to steep hills.

"It's very unusual to see this by a mountain range. It's kind of a freak thing," Fleming said.

The storm, moving northwest, dissipated quickly after the tornado struck. But watches and warnings remained posted for northeastern Colorado.

Later Thursday night, KABC in Los Angeles, California, reported that a tornado warning was issued for west central Riverside County.

March Air Reserve Base near Moreno Valley was closed and its control tower was evacuated after multiple twisters were spotted.

A big-rig truck was overturned and a train was derailed, reportedly by a tornado moving across Riverside County, the CNN affiliate reported.

CNN Meteorologist Chad Myers contributed to this report.

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