Interstate 80 was closed in Green River after the crash and will likely remain so until at least Wednesday, officials said. The roadway runs from San Francisco nearly to New York City.

The crash occurred at 11:37 a.m. under a snow-dusted hill in Green River, Wyo., according to the State Transportation Department. By 5 p.m., the tunnel, which leads traffic west on Interstate 80, had been evacuated and the scene had “been contained,” the department said in a statement.

The Sweetwater County Sheriff's Office has warned of an ongoing "explosion threat" at the crash site, where a tractor carrying explosive transformers was reportedly involved in the pile-up