Police have been warning motorists to stay off the roads or use extreme caution in the suburbs and counties north of Pittsburgh, where rain is freezing on roadways despite above-freezing air temperatures.
The National Weather Service says the icy spots are developing because the ground remains cold enough from a recent cold spell.
State police in Butler, 30 miles north of the city, issued a plea for people to stay off the roads temporarily, and police in Punxsutawney, 60 miles northeast of the city, report they're dealing with multiple crashes.
Social media sites have been buzzing with reports of icy pavement and crashes on Route 28 northeast of the city, as well as Interstate 79 between Portersville and Zelienople (zee-lee-en-OH'-pul) in Butler County.
Copyright 2013 The Associated Press.