MISSOULA (AP) — Freezing rain caused treacherous driving conditions in western Montana on Wednesday morning, causing crashes that blocked lanes on Interstate 90 both east and west of Missoula and leading Missoula Public Schools to cancel classes because buses were unable to run safely.

The eastbound lanes of Interstate 90 west of Alberton were blocked Wednesday morning after semi tractor-trailers jackknifed, blocking both lanes, while other vehicles slid off the icy roadway, officials said.

The Frenchtown Rural Fire District posted photos of vehicles that crashed, slid off the road or had to pull over because the roads were covered with black ice.

About nine miles east of Missoula, eastbound Interstate 90 was down to one lane due for a time due to crashes near the Turah exit, although traffic began moving as conditions improved late Wednesday morning.

Missoula schools initially planned on a two-hour delay to start the school day, but later said classes would not be held.

"Our partners at Beach Transportation have informed us that buses are not able to run the routes due to icy road conditions," the district posted on social media. "All school activities are canceled as well."