Snow and ice-covered roads made driving extremely treacherous Thursday as most schools and civic events were canceled across the region.

The drivers of two semi-trailers were not injured when one truck crossed an interstate median and its cab crashed into the trailer of the other truck.

State police responded to the accident about 3:30 p.m. Thursday on Interstate 70 near Pocahontas in Bond County.

All westbound traffic was stopped as crews attempt to clear the area near mile marker 35, according to Illinois State Police Trooper Jason Ramert.

At 6 p.m., Meteorologist Mark Britt of the National Weather Service in Weldon Spring, Mo., said that by 7 p.m. the storm will have moved to the east away from the Belleville area and would likely be out of the metro-east by 8 or 9 p.m.

He said that as of the time of the call, 3.2 inches of sleet and snow had fallen in Belleville, 1.5 inches in Sparta and 2.3 inches in Marissa where the slushy mess was topped by an icy glaze.

On Friday, clearing was expected with high temperatures in the mid to high 30s, with slightly colder temperatures predicted for Saturday before high temperatures reach into the 40s Sunday.

On Thursday afternoon, Edwardsville School District 7 had already canceled all classes for Friday due to the weather and hazardous road conditions. By Thursday evening, many other area schools had followed suit.

St. Clair Square in Fairview Heights closed early at 4 p.m. Thursday.

Snow plows were criss-crossing the metro-east, leaving most major arteries slick but passable. By 3 p.m. Thursday, nearly 3 inches of snow had fallen in O'Fallon. Later, freezing rain began to fall.

Along Belleville's West Main Street car after car was stuck during the height of the storm at intersections with side streets that were generally unplowed.

Collinsville police worked a rollover accident on Interstate 255 south at Horseshoe Lake Road. Meanwhile, Belleville police were working about the same time on a rollover crash with a vehicle on fire on Illinois 15 near Frank Scott Parkway.

"We've had several reports of cars in ditches and fender benders," Raymert said. "I think the schools had the right idea by closing early to keep people off the roads. But some people still had to get out there and it's causing some issues."

By 1:30 p.m., for instance, heavy snow was beginning to build up on even major roadways in downtown Belleville. Illinois 159 was beginning to be snow-packed despite traffic moving along the roadway.

Raymert said people should stay home if they can.

Illinois Department of Transportation leaders report that they have treated more than 5,000 miles of roads in the metro-east to try to keep them clean. Crews were having the most trouble in the southern portion of the metro-east where more freezing rain and sleet is falling than snow.

The metro-east was under a severe winter storm warning until midnight Thursday. The storm will bring a mixture of freezing rain, sleet and snow, according to the National Weather Service.

Snow and sleet had begun to fall across the region as early as midmorning.

Snow and sleet accumulations could range between 1 and 6 inches, with an additional two-tenths of an inch of ice, the weather service predicted. Strong winds could blow up to 25 mph with temperatures to hover around freezing all day.

Many metro-east schools canceled classes Thursday. Southern Illinois University Edwardsville announced it would dismiss students after noon and Southwestern Illinois College canceled classes after 11 a.m.

The Class 3A Waterloo Sectional championship girls basketball game between Mater Dei and Massac County has been rescheduled to 3 p.m. Saturday at Waterloo High School. The game was originally scheduled for 7:30 p.m. Thursday.

Most afternoon and early evening flights have been canceled at Lambert-St. Louis International Airport. The majority of arrivals and departures from about 1:30-7 p.m have been canceled. Some smaller carriers have canceled all remaining flights into and out of Lambert. Flight status can be found on the Lambert website or by contacting the carrier directly.

The East St. Louis City Hall closed at noon but emergency services will remain available.

The monthly Diva Night event in downtown Belleville, when downtown shops and restaurants stay open later and offer special deals, was canceled for Thursday, the Belleville Main Street Committee announced at midday Wednesday. The News-Democrat also postponed its Bridal Show, scheduled for the Four Points Sheraton in Fairview Heights.

The O'Fallon Public Library closed at 11 a.m. Thursday in anticipation of the weather getting worse.

The snow, sleet and ice may make roads slick and driving hazardous; the ice may cause damage to trees and power lines.

Ameren Illinois prepared Wednesday for the storm by monitoring weather conditions, placing staff and contractors on alert and fueling and loading trucks.

"When severe storms cause power outages, our first priority is to correct potentially life-threatening situations, such as downed power lines or hospitals without power," said Ron Pate, Ameren Illinois vice president of operations and tech services. "We then implement power restoration plans focused on restoring service to the greatest number of customers in the shortest length of time."

If necessary, Ameren will deploy storm trailers filled with materials for field crews performing restoration work. Electricity outages begin to become a serious concern when a quarter inch of ice or more accumulates on power lines.

Customers who experience a power outage immediately should report it to Ameren Illinois by calling 800-755-5000. Customers with mobile devices can visit www.ameren.mobi.

Although people have been advised to avoid travel, not everyone has that luxury. Ben Harris, of Fairmont City, and Justin Ott, of Bethalto, were installing flooring at a shop on East Main Street in Belleville, but hoping their employer would send them home for the day before the conditions get too dangerous.

"I'm a little nervous," Harris said. "If it was up to me, I'd be gone now."

Ott said he was more worried about driving back to the workshop than the trip to Bethalto. "Driving the heavy, rear-wheel-drive work van can be kind of dangerous," Ott said.

Information for this report was contributed by BND reporters Scott Wuerz, George Pawlaczyk, Roger Starkey and Dan Kelley and the Associated Press.