NEW YORK — Rain “flash-freezing” on roads and sidewalks left an icy glaze under feet and tires across much of the northeast on Sunday, causing crashes that claimed at least five lives.

A crash involving 30 to 50 vehicles on Interstate 76 outside Philadelphia killed one person, and two others died in a crash involving multiple vehicles on nearby Interstate 476, police said. In northeastern Pennsylvania, a man was killed after his car overturned on an icy road and he was thrown from it and hit by a commercial vehicle. In Connecticut, police cited slippery conditions in a crash that killed an 88-year-old woman who struck a utility pole in New Haven.

“This is the worst type of winter precipitation to combat, because it can freeze instantly and it doesn’t need to be the whole pavement for vehicles crossing it to have problems,” Pennsylvania Department of Transportation spokesman Eugene Blaum said.

The National Weather Service warned Sunday night that temperatures were expected to drop below freezing in areas from northern Maryland into Philadelphia and up through northern New Jersey. Any remaining moisture on roadways and sidewalks could re-freeze, and drivers were urged to use caution until conditions improve. Temperatures were expected to hit the 40s by midday today in the area.

Kaitlyn Maier grew up in upstate New York but said that didn’t prepare her for the icy conditions she encountered trying to get from her home in Philadelphia to her niece’s baptism.