SHANKSVILLE — The remaining wreckage of United Flight 93 has been buried near the Pennsylvania memorial marking where it crashed on 9/11.

Four shipping containers holding the wreckage were buried in a private ceremony on June 21 in a restricted area accessible only to loved ones of the victims, the Flight 93 National Memorial said in a statement Monday.

The wreckage was scoured for identifiable items in the months before the burial, and workers found a number of items that will be added to the memorial collection. The park service is expected later this year to release a full report of the items collected and how they will be incorporated into the memorial.

The final phase of the memorial is on track to open on the 17th anniversary of the attacks. It will include a 93-foot tower (28-meter) at the entrance with wind chimes for each of the 40 victims, called the Tower of Voices. It’s designed to serve as a visual and audible reminder of the heroism of those on board. Each chime will have a different tone, or voice.

Remains of all the victims were identified after the crash, either through dental records, DNA or fingerprints. Three caskets of unidentified remains were buried at the crash site in 2011.

Now that the memorial is near completion, the time was right to bury the remaining wreckage, Flight 93 National Memorial Superintendent Stephen Clark said. It had been stored in shipping containers in a warehouse. About 95 percent of the airliner was recovered.

United Flight 93 was among four aircraft hijacked by terrorists that day.