The city said Friday that it will search parts of the World Trade Center site again for remains of the Sept. 11 dead after several bones were pulled out of an abandoned manhole — a discovery that stirred up new fury and disbelief among victims' families.

The family members demanded that construction stop at ground zero until remains of all their loved ones are recovered. They also called for state and federal investigations into the failure to completely remove remains from ground zero.

Mayor Michael Bloomberg called an emergency meeting at City Hall that included police, fire officials and the city medical examiner after the discovery of bones Thursday in a manhole in the 16-acre site. Remains as big as arm or leg bones were found, along with personal effects including at least one wallet, officials said.

The meeting yielded a plan that would have utility companies that are inspecting manhole and utility areas be accompanied by staff from the police and fire departments and the medical examiner's office. Searchers will examine about six more manholes in the next few days, officials said.

City officials will also analyze underground areas to see whether there could be places that weren't searched or need to be searched again. Authorities said it is possible that crews will have to tear up surface areas in order to reach those subterranean cavities.

"We'll go out and look at other manholes and other things," Bloomberg said.

At ground zero Friday, in an area far from where contractors discovered the bones a day earlier, people in hooded white suits went in and out of a white tent next to a police van and a garbage bin.

Police and forensics experts were digging through dirt and other material pulled from the manhole in search for more remains, said an official who spoke on condition of anonymity because of instructions not to speak publicly about the matter.

The discovery of bones angered family members, who want answers about why remains are still turning up five years after the attacks. The families said officials rushed to clean the site of steel and other debris without bringing in experts to look for remains.

Diane Horning said that part of her son's body was located more than four years ago not far from where the bones were pulled from the manhole.

"Oh my God, is that more of Matthew?" she said Friday of the latest discovery. "But it's been sitting there for over five years."

Chief Medical Examiner Charles Hirsch told The Associated Press as he headed inside for the meeting, "We've been in touch with the families and expressed our concern."

Construction work on the Sept. 11 memorial, the 1,776-foot Freedom Tower and a transit hub continued without interruption Friday, said Steve Coleman, a spokesman for the site's owner, the Port Authority of New York and New Jersey.

Construction workers assigned to the transit hub found remains in the manhole Thursday morning.

A Consolidated Edison electrical crew had excavated the manhole earlier in the week. The debris it initially removed from a vacuum-like machine has been sent to the city medical examiner's office, officials said.

The remains of the 2,749 killed — 40 percent of whom have not yet been identified — are likely "in ground zero, under ground zero and certainly on the buildings surrounding ground zero," said Sally Regenhard, whose firefighter son was killed on Sept. 11.

More than 750 bone fragments have been removed in the past year from a vacant skyscraper that the south tower collapsed into. Cleanup has not begun at another damaged building on the site's outskirts.

In all, some 20,000 pieces of human remains have been found, but the DNA in thousands of the fragments — some just slivers of bone — was too damaged to yield matches to victims.

When forensic scientists exhausted available processes to identify those remains, the city told families last year that the project was taking a break, perhaps for years, until new DNA technology could be developed.

But last month, Hirsch said that new methods had been created by a Virginia company that works on Sept. 11 bone fragments, and that new identifications were likely.