A semi-trailer jackknifed Saturday around 12:30 p.m. on I-90 Saturday, about seven miles west of Big Timber.
The accident blocked both lanes of I-90 westbound, according to the Montana Department of Transportation. Vehicles were getting around on the shoulder, but it's unknown whether a detour will be put in place, the MDT said.
The roadway is slushy, with intermittent snow and ice.
Earlier in the day, west of Red Lodge, a bus driving to the Stillwater Mine on Montana Highway 78 became stuck at the bottom of Roscoe Hill, and a semi-trailer going the other direction also became stuck, blocking both lanes of traffic.
As of 11:45 a.m., the MDT said, that blockage was cleared.
The road condition at the time was snow and ice.