NEW YORK (AP) – A seven-alarm blaze in a skyscraper abandoned on Sept. 11 killed two firefighters and raised concerns that toxic substances in the building could spread in the plume of smoke that trailed above ground zero, although officials said preliminary tests showed no danger.

The fire in the former Deutsche Bank office building brought the stench of smoke and the screech of sirens back to an area still recovering from the Sept. 11 terrorist attacks. It was another tragedy for a firehouse that had already lost 11 members in the attacks.

“Today’s events really are another cruel blow to our city and to our fire department,” Mayor Michael Bloomberg said.

He said the fire had “expanded our loss.”

Bloomberg sought to reassure residents that the asbestos and other toxic substances in the building, dumped there in the collapse of the twin towers, likely did not present a significant health risk. Air-quality tests so far showed no danger, he said.

“Having said that, we are extremely careful. We don’t want to prejudge anything,” the mayor added, noting that tests were to continue overnight. For the moment, he said, health authorities did not see a need to establish any “frozen zone” around the building, except what was needed for firefighting. Bloomberg said initial concerns the building could fall were unfounded.

One of the firefighters killed was identified as Joseph Graffagnino, 34, of Brooklyn. A firefighter for eight years, he was a member of Ladder 5.

The name of the other slain firefighter was not immediately released because officials hadn’t been able to reach his family. Bloomberg said both firefighters had become trapped.

Five or six other firefighters were taken to a hospital but were expected to be released, Bloomberg said. No civilians were hurt.

The acrid smell of smoke, which hung over the neighborhood for days after Sept. 11, returned to lower Manhattan along with the wail of emergency vehicles. More than five dozen fire vehicles, with more than 270 firefighters, responded to the blaze as pieces of burning debris fell from the building to the streets.

“We heard this crashing,” said Elizabeth Hughes, who saw the fire start from her rooftop deck across from the tower, already decimated by the Sept. 11 terrorist attacks. “And then a huge fire that went up three floors fast. It was massive. … Oh my God! I can’t even go in and get my cats.”

Hughes called 911, grabbed some of her things and ran, she said.

The blaze began about a dozen floors up and was burning on multiple floors at the building, steps from where 343 firefighters lost their lives on Sept. 11, 2001. Construction crews had already dismantled 14 of the building’s 40 stories – reaching the 26th floor on Tuesday.

Some firefighters used stairs to reach the burning upper floors; others smashed out the building’s windows to let in more air to reach the flames.

More than two hours after the blaze was first reported, it was declared a seven-alarm fire. Officials pushed onlookers further back from the building and set up a command post on the West Side Highway. Officials could be seen poring over a map of the area, and scaffolding on the sides of the building was aflame. Smoke was visible from midtown Manhattan and the New Jersey side of the Hudson River.

By late Saturday evening, nearby residents who had been evacuated from their homes were told they could return.

The cause of the fire was unknown.

The building at 130 Liberty St. has become a constant headache for redevelopers in the nearly six years since the attacks. The 1.4 million square foot office tower stood as a downtown Manhattan eyesore, contaminated with toxic dust and debris after the World Trade Center’s south tower collapsed into it.

Efforts to dismantle the skyscraper were halted by a labor dispute last year, along with the ongoing search for the remains of attack victims.

More than 700 bones and fragments were discovered in the contaminated skyscraper from mid-2005 to June of this year, including some positively matched this year to a previously unidentified victim. The last bones found at the building were in March, leading city officials to conclude their search three months later.

There was another weeklong shutdown of work in May, when a 22-foot pipe fell through the roof of a nearby firehouse from the 35th floor.

Two years ago, redevelopment officials said the building contained excessive levels of seven hazardous substances, including dioxin and lead. As part of the tear down, a dozen air quality monitors were installed in the area around the building.

Emergency management officials said authorities were continuing to investigate whether the smoke at the scene could pose any environmental danger.

AP-ES-08-18-07 2306EDT