Traffic on the Interstate grinds to a halt during the rush hour after a semi smashes into a Rock County snow plow clearing the inside median.

The Rock County Highway Department says the crash occurred just before noon Friday on southbound I-39/90 near Highway 11.

At the time of the incident the plow was clearing snow on the inside median when it was struck on the passenger side by a semi tractor trailer.

The State patrol says the impact caused the semi to jackknife and block all southbound lanes of the Interstate. The semi driver , a 59-year-old Milwaukee man was fatally injured.

The plow driver wasn’t hurt.

Traffic is currently being re-routed while the State Patrol investigates. The closure is expected to extend into the evening commute.