MISSOURI, USA (AP) — At least nine people have died in weather-related crashes in several Midwestern states amid a storm that dumped nearly a foot of snow in places, forced schools to close and snarled traffic, authorities said.

The wintry weather was part of a storm system that hit parts of the Midwest and was expected to extend into the north-east through today, the National Weather Service said.

In Missouri, the storm dumped three to nine inches (7.6 to 22.9 centimetres) of snow across much of the state. Much of Missouri was under either a winter weather advisory or winter storm warning, yesterday.

The Missouri State Highway Patrol said three people were killed Sunday night when a driver lost control and overturned on US 67 in St Francois County in the eastern part of the state. A motorist who was stranded after a previous crash and two good Samaritans who were trying to help were struck.

And in mid-Missouri’s Callaway County, an 18-year-old was killed when his vehicle went off the side of Missouri 94 and overturned.

The patrol also said in a tweet Sunday night that it had responded to 525 calls from stranded motorists and to nearly 560 other traffic crashes. The University of Missouri was starting classes late Monday because of the storm.

In Nebraska, a crash Sunday on Interstate 80 north-east of Lincoln left three passengers ages 10, 15 and 19 dead. The crash happened when the driver of an eastbound sport utility vehicle lost control amid slick conditions, struck another eastbound vehicle before veering into the median, rolling and entering the westbound lanes. The SUV was then hit by a car and a pickup truck, according to the Nebraska State Patrol.

In Kansas, the storm brought up to 11 inches (27.9 centimetres) of snow. The Kansas Department of Transportation said multiple roads were partially or completely snow covered. A 21-year-old man died Sunday when a pickup truck in which he was riding overturned on an icy Wichita road.

Weather also is believed to be a factor in a collision yesterday between an SUV and a pickup truck that killed a woman and her adult son along a road east of Indianapolis, following a night of snowfall, police said. Fifty-four-year-old Amy Cox and her 24-year-old son, Isaac Cox, of New Palestine, were pronounced dead at the scene.

At St Louis Lambert International Airport, about 20 departing flights and 20 arriving flights were cancelled as of 6:00 am yesterday due to the winter storm. Lambert said in a tweet that crews worked through night and the landing strips were in good condition.

The storm also closed the University of Missouri and Emporia State University in Kansas.