DES MOINES, Iowa (AP) -

Several major highways in Iowa have been partially closed due to poor road conditions from a major overnight snow storm.

The state Department of Transportation says on its website that several locations along Interstate 80 remain closed Thursday morning. They include an exit near Council Bluffs by the Nebraska state line, and exits near mile markers in central Iowa.

On Interstate 35, roads are blocked along exits near Williams and Coulter in north Iowa.

The agency says many of the closures or blockages are due to numerous road accidents. State officials have warned drivers to stay off the road because of whiteout conditions in some areas.

The National Weather Service has issued a blizzard for most of Iowa through Thursday evening. A winter storm watch also is in effect.