Construction workers in New York have discovered 74 bone fragments from victims of the 11 September 2001 attack on the World Trade Center.
Part of the WTC's south tower crashed into the building
The remains were found mixed in with roofing material at the condemned Deutsche Bank building, which stands next to Ground Zero.
The office block bore much of the blast when the twin towers collapsed in 2001, killing 2,749 people.
More than 40% of those killed on 9/11 have not been formally identified.
"The work on the roof has only just started, so maybe there will be more discoveries to come as the work progresses," said a spokeswoman for the chief medical examiner's office, Ellen Borakove.
All the fragments would be subjected to DNA testing, Ms Borakove said. If no match can be made, they will be stored with more than 9,000 other unidentified fragments.
"If new technology becomes available that might help with identification, then of course we will test them again," Ms Borakove said.
The Deutsche Bank building, which is contaminated with asbestos, lead and dust, has been earmarked for demolition for some time, but the work has been delayed by legal wrangles.
Some of the victims' relatives have urged the Lower Manhattan Development Corp (LMDC) rebuilding agency to allow forensic experts to search the building.
Construction workers have been instructed to look for human remains and notify the medical examiner's office when they find them.
Many of the relatives plan to ask New York Mayor Michael Bloomberg to insist that a team from the medical examiner's office is on-site at all times.
"This is an abomination that we are putting this on construction workers," said Sally Regenhard, the mother of a firefighter killed at the World Trade Center.