POCATELLO, Idaho (AP) — A thick layer of fog is believed to have caused a roughly 30-vehicle collision on an Idaho interstate, state police said.

The collision occurred Monday morning on eastbound Interstate 86, near milepost 56, west of Pocatello, near the Pocatello Regional Airport. Police said the fog caused visibility to significantly decrease in a short amount of time.

“Due to the fog, vehicles slowed down suddenly,” the Idaho State Police said in a news release. “Commercial and personal vehicles collided with one another causing a chain reaction of approximately thirty vehicles.”

One person with minor injuries was taken by ambulance to a hospital. Several others were taken by personal vehicles, police said.

Traffic on I-86 was blocked between exits 56 and 59 for seven hours, allowing for emergency responders and tow trucks to assist those involved and to clear the scene.

“This is unusual to have this many vehicles involved, but when we’re driving in winter conditions in Idaho, we need to be prepared for fog, sleet, snow, all those conditions that would cause us to have a crash,” Lt. Michael Winans said.