The remaining wreckage of United Flight 93 has been buried near the Pennsylvania memorial marking where it crashed on 9/11.
Flight 93 National Memorial says in a statement Monday that four shipping containers holding the wreckage were buried in a private ceremony on June 21.
The burial was in a restricted area accessible only to loved ones of the victims.
United Flight 93 was en route from Newark, New Jersey, to San Francisco on Sept. 11, 2001, when hijackers seized control with the likely goal of crashing into the U.S. Capitol.
The 9/11 Commission concluded the hijackers downed the plane as passengers revolted, in a field in Shanksville, about 70 miles (113 kilometers) southeast of Pittsburgh.
The wreckage was scoured for identifiable items in the months before the burial.