CHESTER, Wis. (AP) — Authorities say nine dairy cows were killed when a semi-trailer hauling more than three-dozen cattle slid down an embankment of a Wisconsin highway and tipped over.

The 61-year-old driver had pulled over on the shoulder of a ramp on U.S. Highway 151 in Chester township Thursday night when it began to slide on the soft ground. The driver was unable to correct the wheels to prevent the trailer from toppling over.

The Dodge County Sheriff’s Office says the trailer was carrying 38 Holsteins. Several area dairy farm workers aided in rescue and recovery.

Chester is located about 70 miles northeast of Milwaukee.