CHICAGO (CBS)– The Illinois Department of Transportation is warning drivers of slick road conditions amid active snowfall.

According to IDOT, approximately 100 salt trucks have been deployed in Cook and collar counties.

Due to the increased rate of snowfall, IDOT representatives said driving visibility is a concern and slow driving conditions is expected.

Illinois State Police reported that between 7 a.m. and noon Sunday, troopers responded to 30 to 40 calls for service on I-57 and I-80 due to slick roads.