DENVER (AP) — A fiery crash involving a tanker truck shut down a stretch of Colorado’s main east-west highway on the outskirts of Denver on Thursday.

The tanker was fully engulfed in flames after the crash on Interstate 70 near Morrison, 18 miles (29 kilometers) west of the city, the Jefferson County Sheriff’s Office said. Up to six other vehicles were involved.

That section of I-70 in the foothills was expected to be closed though the afternoon, the Colorado Department of Transportation said.

It wasn’t immediately clear what the tanker was carrying but the transportation department said the crash resulted in a hazardous materials spill.

Television news helicopter footage didn’t show any flames remaining. The tanker truck was pulled off on the shoulder.