Manholes jarred loose following underground explosion in Pittsburgh

Crews are near the U.S. Steel tower after reports of an underground explosion Tuesday afternoon.

It's believed that a transformer exploded just before noon, sending smoke billowing out of at least two manhole covers on Grant Street, near Seventh Street.

Pittsburgh Public Safety and utilities crews responded to the scene.

Christian Cole, who was nearby, provided video to KDKA Radio that shows thick smoke coming out of a manhole cover.

A loud boom was heard by witnesses nearby the reported explosion. At least one manhole cover was jarred loose.

No injuries have been reported and crews are monitoring for any air contaminants.

Traffic restrictions were in place around the incident.