ROANOKE RAPIDS, N.C. (From news reports) -- Four people were injured, including one critically, from steam released from a valve at a Roanoke Rapids paper mill.

The incident happened at WestRock around 1:30 p.m. on Aug. 25.

"Just to make you aware, we had a machine blow up at 100 Gaston Road," radio traffic reported about the incident.

United Steel Workers said two of the employees had to be airlifted from WestRock. The union also has a team helping the employees' families.

Roanoke Rapids police said the U.S. Occupational Safety and Health Administration will likely be investigating. The cause of the incident remained under investigation, the spokesman said.