DENVER >> A major storm dumped over 4 feet of snow in northern Colorado before ending today, leaving thousands without power and continuing to make travel hazardous in the mountains and foothills west of Denver.

The storm shut down a highway that connects Denver to Colorado ski resorts for much of the day Thursday, stranding some people in their cars for hours. Portions of Interstate 70, the state’s main east-west highway, first closed as the storm moved in Wednesday night.

The Colorado storm, which began Wednesday night, delivered the slushy, wet snow typical for March, one of the snowiest months in Denver, which got up to about 10 inches of snow. Between 10 and 20 inches fell in the metro area and 2 to 4 feet in the foothills, the National Weather Service said.

Snow reports were still being collected but the highest accumulation so far was 53 inches in Nederland, a mountain town near Boulder, the weather service said.

Trucks that got stuck in the snow, some without the tire chains required to travel the route, were the main reason traffic shut down on the highway after the storm moved in. Drivers stuck behind them had to wait for specialty tow trucks to come in and haul the big rigs out of the way to allow traffic to flow, said Sgt. Patrick Rice of the Colorado State Patrol.

Rice urged any drivers setting out to bring food and blankets in case they get trapped.

While a boon to Colorado’s ski industry, the extreme conditions shut down several ski resorts Thursday. While some of those were back open today, Eldora Mountain, near Nederland, was urging people to stay home and be patient until crews could dig out lifts, do avalanche control and clear parking lots and an access road. A six-wheel-drive grader went off the road while trying to clear it, the resort said.

The storm also closed numerous schools and government offices Thursday and Denver area schools were closed again today.

About 23,000 customers were without power in Colorado, primarily in metro Denver and along the Front Range, according to poweroutage.us.

Since the storm is the rarer kind that brings more snow to the eastern half of the state rather than the higher mountains in western Colorado, it is not expected to do much to feed the Colorado River, which supplies water to more than 40 million people. The snow fell mainly on the east side of the Continental Divide and will boost the snowpack for the South Platte River basin to well above average, state climatologist Russ Schumacher said. The Arkansas River basin snowpack may be pushed above average after lagging behind a bit for much of the winter, he said.

About 800 flights were canceled at Denver International Airport on Thursday but only about 20 were scratched today and more than 200 were delayed, according to Flightaware.com.