Law enforcement agencies and emergency vehicles have been responding to several crashes on I-90 west of Missoula early Tuesday morning.

Sergeant Jeremiah Peterson with the Missoula County Sheriff's Office said there is what he described as a 'wall of fog' just past the Wye that has brought visibility to near zero.

"The visibility is really poor in some spots," Peterson said. "We've had three crash out there so far, luckily no serious injuries. It's amazing. You get to the Wye and there's just like a wall of fog, and that's where it starts."

The Montana Highway Patrol said the freezing fog is causing black ice, and with visibility near zero, all agencies urge drivers to reduce speed.