Five people died and dozens were injured in more than 650 crashes on snow-covered Missouri roads, and authorities said up to 50 vehicles collided on a freeway in Iowa.

The Missouri State Highway Patrol said the crashes started Sunday afternoon as snow began falling. Less than 2 inches accumulated, but the snow was treacherous because temperatures dropped rapidly from the high-30s to the single digits throughout the day, said meteorologist Gene Hatch with the National Weather Service in Springfield.

"The initial amount of light snow that melted on the roads froze as temperatures hit the freezing point," he said. "The roads went from wet to icy very quickly, and once the water on the roads froze, the snow that was falling began sticking, making it even slicker."

The largest crash happened on Interstate 44 near Marshfield, about 150 miles (241 kilometers) southeast of Kansas City. Besides the 60 to 80 damaged vehicles, another two dozen vehicles became blocked and unable to move, said patrol Sgt. Jason Pace. The pileup killed a 55-year-old man from Glendora, California, whose name wasn't immediately released. The interstate was closed for several hours while crews cleared the wreckage.

Pace said nearly 350 crashes and 50 to 55 injuries were reported in the 18-county area he is responsible for in the southwest part of the state.

One 12-vehicle pileup on I-44 in a six-county region in south-central Missouri killed Deborah Anderson, 63, of Ballwin, the highway patrol said.

Three other crashes on snow-covered roads elsewhere in the state killed Heather Sapaugh, 32, of Salem; Michael Marquette, 28, of Mexico, Missouri; and Jessulyn Williams, 26, of Norborne.

In Iowa, authorities closed part of Interstate 35 near Ames on Monday after up to 70 vehicles collided on the snow-covered pavement. Officials said one person died and three to five others were injured. The identities of those killed or hurt in Iowa were not released.

Authorities said the wrecks were caused, in part, by drivers trying to enter the freeway and crashing into existing accidents.

Story County Sheriff's Office Capt. Barry Thomas told The Des Moines Register he couldn't see from one end of the wrecks to the other.