DOWS — Authorities in Iowa say two people have been killed and several more injured in a highway accident involving 25 vehicles.

The Iowa State Patrol said the crash happened Thursday morning along southbound lanes of Interstate 35 about 60 miles north of Des Moines, between the exits to Dows and Webster City. Two people were killed and seven were injured.

Authorities say poor visibility caused the accident when drivers were unable to see vehicles that had slowed or stopped, causing a chain reaction of crashes.

Officials are advising drivers to stay off roads in Iowa until midnight due to a major snow storm. They say visibility in northern Iowa and along other rural roadways are near zero.