Four people received minor injuries and hundreds more were trapped in cars, a bus and ski lodges after two avalanches slid across the road in Big Cottonwood Canyon on Tuesday afternoon.

The avalanches released naturally at about 2:30 p.m., said Lt. Dennis Steadman, Salt Lake County Fire Department spokesman. Emergency crews used probe poles and avalanche rescue dogs to search the slide, which left snow and other debris more than 25 feet deep across a 200-yard stretch of the road.The Utah Department of Transportation reported at 8:30 a.m. Wednesday that Little Cottonwood Canyon, which was closed after the slides, was open to traffic but restricted to vehicles with snow tires and chains.

Big Cottonwood Canyon was still closed later in the morning, a Salt Lake County sheriff's dispatcher said. Officials were hopeful the highway could be opened later in the morning.

An avalanche warning remained in effect Wednesday in Wasatch Mountain canyons from Provo to Logan, said Tom Kim-brough of the Utah Avalanche Forecast Center at the Salt Lake office of the National Weather Service.

The first avalanche Tuesday rolled out of a drainage above the area known as the S-turns about 2 1/2 miles from the mouth of Big Cottonwood Canyon, hitting a car carrying four passengers. All four people were injured slightly when the snow shattered the car windows and knocked the car off the road, Steadman said.

Two people, treated and released at LDS Hospital, were Patrick Brady, 23, and Melinda Richards, 18, both of Salt Lake City. The other individuals apparently were treated at the scene and released.

Moments after the first slide, another avalanche ran off Storm Mountain - one of the biggest slide areas in the canyon - a mile up the road from the first slide, trapping about 30 people in cars and a Utah Transit Authority bus between the two slides, authorities said.

Search-and-rescue crews on snowmobiles pulled the four injured people to safety and took them on a snow tractor to ambulances waiting below the slides. The trapped motorists boarded the bus, where they and the other passengers stayed warm while waiting for road crews to punch through the wall of snow that blocked the road.

About 75 people - county fire-fighters, deputy sheriffs, the sheriff's search and rescue unit, the Red Cross and ski patrollers from Brighton and Solitude - were involved in the rescue effort, Steadman said.

Meanwhile, the hundreds of skiers stranded in Brighton during the rescue weren't sure if they were going to get home Tuesday night, said Don DeSpain, owner of the Brighton Village Store.

"We've got a lot of people sitting in our ski shop and cafe. We don't really have accommodations here," DeSpain said, adding he would keep his cafe open until everyone was allowed to leave.

A little farther up the road, skiers were making the best of the situation in the Brighton Lodge, said a lodge employee who declined to give her name.

"It's my day off. I'm up here trapped like everyone else," she said. "We've got about 300 or 400 people here, a lot of cars in the parking lot, plus people waiting for the bus.

"Our bartender just came down and said `What a zoo! Give me 50 dollars' worth of quarters.' It has to be an adventure, as long as no one is seriously injured or killed."

By 8:45 p.m., road crews had cut a path through the avalanche debris and the first of four buses had arrived at Brighton to take people down the canyon. The buses and cars formed a caravan and drove down the canyon by about 11 p.m. The road then closed for the night.

Over the ridge in Little Cottonwood Canyon, a smaller avalanche off a south-facing slope slid across the road in the town of Alta and stopped traffic for a short time while rescuers probed a 40-yard stretch of 4-foot-deep snow for possible victims.

The ski lifts already had closed when a slope near the U.S. Forest Service guard station slid a little after 4:30 p.m., Alta Central dispatcher Jared Higgins said.

Some people and a bus were on the road when the slide hit, but witnesses reported that no one was caught, Higgins said. The rescue operation, which involved two lines of people searching the snow deposit with probe poles, was a normal precaution, he said.

The road opened at about 5:45 p.m., and as soon as everyone was out of the canyon the road closed for the night, Higgins said.

The slide sloughed naturally during a heavy winter storm that had been dumping snow at the rate of about an inch an hour all day.

Although the avalanche danger was not as high in some of the outlying areas, Kimbrough said early Wednesday that the avalanche warning was continued as a precaution.

The danger of avalanches is high on slopes steeper than 30 degrees. Some spontaneous avalanches are possible along the whole Wasatch Mountain range.