Update 11 a.m. EDT July 19: Letterkenny Army Depot Commander Col. Steven Ledbetter said a small explosion happened around 7:20 a.m. in a paint area at one of the depot's production facilities.
“In this particular production facility, it’s vehicles and some major end-items (and) large pieces of equipment,” Ledbetter said. “No munitions.”
He said four people were taken to hospitals with injuries after the incident.
Authorities do not believe the blast was connected to terrorism. Officials continued to investigate the cause of the explosion on Thursday.
Update 10:20 a.m. EDT July 19: Col. Steven Ledbetter, the commander at Letterkenny Army Depot, told WPMT that a small explosion and fire Thursday morning left four people injured.
Three people were flown to a Maryland hospital in serious condition, the news station reported. A fourth person was taken to Chambersburg Hospital with unknown injuries, according to WPMT.
Original report: Authorities at Letterkenny Army Depot confirmed in a series of since-deleted Facebook posts Thursday morning that an explosion was reported at the depot. The incident happened around 7:15 a.m., according to WPMT.
Officials with the volunteer Franklin Fire Company said three people were flown from Letterkenny after firefighters responded Thursday morning to an "explosion with burn victims." The Franklin County Office of Emergency Management also told Fox News three people were flown from the Army depot after the blast.
It was not immediately clear what caused the explosion.
A spokesman for Letterkenny Army Depot told WHTM-TV that authorities do not believe the blast was the result of a terrorist attack. Employees told the news station that the explosion happened in an area of Building 350 used for painting and that they were "worried about peers who ran out of (the) building screaming (and) on fire."
Established in 1942, the 18,000-acre Letterkenny Army Depot employs more than 3,600 people in Franklin County. Its mission is to “deliver superior maintenance, manufacturing, logistics, life cycle support and service worldwide to the Joint Warfighter and our International partners.”