From today's DC Post [1]:

There were reports late yesterday of two incidents in which organized fireworks displays injured people. An employee of Pyro Shows Inc., the company that orchestrated the Mall fireworks, was severely injured when a shell exploded about 15 minutes after the show ended. The man, whom police did not identify, was transported to a hospital in a U.S. Park Police helicopter. A second man was also injured, Line said, but was treated at the scene and moved in an ambulance.

Line said the Tennessee-based company often tests shells the afternoon before a show, and the shell that injured the two men was a leftover that had not been tested.

UPDATE (10:45am): The severely injured Pyro Shows worker is a 42-year-old male and has suffered third-degree burns down the right side of his body. Still no info on his identity yet. Knoxville media hasn't picked up the story as of this post.

Pyro Shows is based in LaFollette in Campbell County.

UPDATE (12:00pm): The injured worker has been identified as Bob Crapsey of Caryville. I tipped off WVLT-TV [2] to this story this morning and they have since spoken with Crapsey's wife.