A fire Friday afternoon raged through the headquarters complex of Flight 93 National Memorial in Pennsylvania and destroyed three buildings before the flames could be put out. None of the staff or volunteers at the national memorial were injured, but officials fear some of the archival and curatorial collections, including the flag that flew over the U.S. Capitol on September 11, might have been destroyed.

"The lost buildings served multiple functions for the operation of the memorial, including administrative and staff offices, conference facilities, and storage of some of the memorial’s archival and curatorial collection," the Park Service said in a release. "Of greatest concern are those collections. Fortunately, only 10 percent of the Flight 93 National Memorial collection was kept on-site in this building, and many of those objects are stored in fireproof safes. Until the area is declared safe, however, staff will not be able to access the collection storage area and determine the condition of any other objects."

Park Service officials said staff was able to save oral history collection and the photo collection that were kept in the facility. The Congressional Gold Medal awarded last month was not on-site at the time of the fire, they added.

"The 9/11 flag that flew over the United States Capitol on September 11 and was presented to the park just last month during the annual 9/11 observance was stored on site, though, again, staff have not yet been able to access the collection area to determine the condition of the flag," the agency said.

The cause of the fire, which was reported shortly after 3 p.m. local time, was under investigation by local fire officials, but National Park Service special agents were en route to the site and were to take over the investigation upon their arrival. 

Because of the distant location of these buildings from the memorial plaza and the access road to reach the memorial, Flight 93 National Memorial will be open for visitors on Saturday morning at the regular time.