Emergency crews are being dispatched to dozens of minor traffic accidents as the first of what is expected to be up to 6 inches of snow falls on the region.

In Castle Shannon, dispatchers said, a car slid into a house; in Wilkinsburg, a minivan flipped over, likely due to icy roads. No one was hurt in either accident, dispatchers said.

Much of the region remains under a winter storm warning, which will stay in effect until 7 p.m. tomorrow. A winter storm warning means significant snowfall, sleet, freezing rain and ice are expected and will make travel very difficult or impossible.

Many school districts around the region tonight were posting two-hour delays for tomorrow morning.

Areas north of Pittsburgh are expected to get the most snow. Butler and Lawrence counties likely will see 6 to 8 inches of snowfall by the end of the night, meteorologist John Darnley said.

Four to 6 inches of snow could fall on northern Allegheny County, alternating to freezing rain in the early morning hours and back to snow later tomorrow morning, he said.

Freezing rain and ice will dominate father south in Greene and Fayette counties, Mr. Darnley said.

The precipitation is expected to change back to snow by tomorrow afternoon.

This morning's snow prompted numerous school delays and created slick driving conditions. In Pittsburgh and the immediate suburban areas, many roadways were covered with snow in the predawn hours. Bridges and overpasses particularly were dangerous. Downtown streets also were snow covered and slippery by 5 a.m.

Heavier snow fell to the south of the city, creating traffic nightmares for areas such as Morgantown, W.Va.

Conditions likely will be much worse across the area by tomorrow morning's rush hour.

See information about school closings, early dismissals and delays on KDKA.com, the Post-Gazette's news partner.

Check out the latest conditions and forecast. Commuters also can access the updated traffic conditions.