CLAIRTON — Crews are responding to an explosion at a U.S. Steel plant near Pittsburgh.

Some workers reportedly suffered minor to moderate injuries in the blast just before 10 a.m. today at the United States Steel Corp.'s Clairton Coke Works.

A company spokeswoman said she could not immediately confirm the news. An official with the United Steelworkers said the union is looking into the report.

Aerial television video showed smoke rising from the sprawling plant and the area swarming with emergency workers.

The plant is about 20 miles south of Pittsburgh. A maintenance worker died in an explosion there in September.