DNA tests have identified the remains of three more people who died in the attacks on World Trade Center on 11 September 2001.
Victims' families are demanding a wider search
They were American Airlines Flight 11 stewardess Karen Ann Martin, passenger Douglas Joel Stone, and a man whose relatives have requested anonymity.
The news came as families rallied at Ground Zero to demand a wider search.
More than 200 body parts have been found since workers discovered remains as large as leg bones two weeks ago.
The original search for remains ended in 2002 after about 20,000 human fragments had been unearthed.
But recent construction work has uncovered further remains, indicating that some manholes and utility cavities could have been missed in the original search.
The remains identified on Thursday were not found in recent searches. Ms Martin and Mr Stone were both on board the first plane which hit the World Trade Center.
Families of more than 1,100 of those who died have never received any remains of their loved ones.
Human remains were found beneath a manhole at the site
Recent discoveries have sparked angry calls for construction to be halted, and answers as to why the first search was not exhaustive.
The city has responded by promising to hire 10 forensic anthropologists to help find and identify additional remains, but some victims' families say this is not enough.
"We demand a scientific, well-organised controlled survey of Ground Zero by a reputable entity," a statement by organisers of Thursday's rally said.
"We must show our absolute solidarity at the site where the remains of the 9/11 dead have lain ignored and unburied for over five years.
"It is time to stand up and be counted. There can be no more haphazard discovery of human body parts and personal effects."
New York Michael Bloomberg has said that the city should be proud of the original search, in which almost all areas were gone through.
The discovery comes just weeks after the fifth anniversary of the 9/11 attacks, in which more than 2,700 people died.