The Northeast endured a “flash freeze” on Sunday, resulting in deadly crashes and flight delays across the region, and the Northwest had similar problems.

Icy runways forced the closure of Hartford’s Bradley International Airport in Connecticut, and morning delays were up to an hour at Philadelphia International Airport and 40 minutes at John F. Kennedy International in New York, according to a USA Today report.

Meanwhile, a crash that involved up to 50 vehicles outside Philadelphia on Interstate 76 resulted in the death of one individual, and two others were killed in a multi-vehicle crash on Interstate 476 nearby. A man died after his car flipped in northeastern Pennsylvania on an icy road. And in Connecticut, an 88-year-old woman died after her car collided with a utility pole.

Black ice was a big problem throughout the region as rain fell on frozen roads, causing hundreds of crashes. It has since warmed up and the ice has largely melted, so drivers on Monday shouldn’t experience as many problems.

However, not all areas will escape further freezing. The National Weather Service forecasted yesterday that Sunday night would result in more freezing temperatures in northern Maryland and in the Philadelphia area and into northern New Jersey, which could re-freeze remaining moisture on the roads. Temperatures were expected to return to the 40s by midday.

The George Washington Bridge, which links North Jersey to New York City, was closed for hours due to the ice, according to the report.

More than 200 crashes were reported in the state of New Jersey before the ice finally melted. The roads had been pre-treated with salt, but the rain washed it away and then froze.

Four bridges linking Philadelphia to New Jersey had to be closed for treatment. Authorities have to be extra cautious with bridges because they generally freeze before roads do.

The Northwest also had its share of problems. A massive car wreck involving a dozen tractor-trailers on Interstate 84 in Oregon near the Idaho border resulted in 12 people being injured, including one man who was sandwiched between two tractor-trailers — a photograph of him in his predicament went viral over the weekend.