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CHAMBERSBURG, Pa. (CBS/AP) — The U.S. Army says one of five civilian employees injured in an explosion and fire at a military depot in Pennsylvania has died. He has been identified as 29-year-old Eric Byers of Satillo, Huntingdon County.

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Two others remain hospitalized in critical but stable condition following the explosion at the Letterkenny Army Depot.

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The explosion occurred in a painting area for vehicles on Thursday morning at the facility in Chambersburg, about 160 miles west of Philadelphia. The cause is under investigation.

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The Lehigh County Coroner’s Office says Byers was handling chemicals when the flash fire occurred. Byers’ cause of death was determined to be thermal injuries due to a fire. The coroner ruled his death as an accident.

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The depot handles air defense tactical missile ground support equipment, mobile electric power generation equipment, Patriot missile recertification and route guidance vehicles.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)