James Lomma, president of New York Cranes, said that the incident occured when a third collar was being attached to the year-old Favco 440 after it had been climbed. He said that the collar slipped, and knocked out two lower collars. Without any connections to the building, the crane toppled over. The crane was about 200ft (61m) high when the accident occurred.

The crane fell on top of nearby buildings on 50th Street.

Lomma added that he did not know why the collar slipped, but he said that the crane climbing operations were carried out by a construction subcontractor.

Main contractor on the site was Reliance Construction, which issued a statement. “We express our deepest sympathies to the families of the victims and to those who have been injured as part of this devastating accident.  We are cooperating fully with all government agencies involved.  We subcontracted out the work at this site and the crane itself was supplied by New York Crane.  We have already launched our own internal investigation to understand exactly what caused this tragedy and we believe it is prudent not to comment further at this time.”

The crane fell on top of nearby buildings on 50th Street.

A New York Fire Department spokesman told the New York Times that four people were killed and 13 people were injured, three critically.

The International Union of Operating Engineers Local 15 union announced the death of one of its members, Anthony Mazza, in the incident. Mazza was an 18-year veteran of the union.

The New York Times named the other three killed as Brad Cohen, Aaron Stephens, and Wayne Binder.

“On behalf of the 5,000 members of this local union, our thoughts and prayers are with the families of our fellow building tradesmen and civilians who also lost their lives,” the union said in a statement, “as well as for those who were injured or displaced due to this very tragic accident.”

It also named union member John Dellaporta as one of the injured.