One person was killed and dozens injured in an explosion on the morning of 11 August at a U.S. Steel is located near Pittsburgh, Pennsylvania. Two people are reported missing, according to emergency officials.
News agencies are publishing footage showing thick smoke over the plant.
The plant specialises in the production of coal coke for metallurgy. About 1200 people work here. The enterprise has been in operation since the early 20th century.
The Allegheny County Health Department sent specialists to monitor air quality in the area of the explosion. The cause of the accident has not yet been determined.