Lower Manhattan, south of 14th Street, was off-limits, except for rescue and recovery workers. There were also about 400 working dogs, the largest deployment of dogs in the nation's history. Organization New York City Office of Emergency Management was the agency responsible for coordination of the city's response to the attacks. Headed by then-Director Richard Sheirer, the agency was forced to vacate its headquarters, located in 7 World Trade Center, within hours of the attack. The building later collapsed. OEM reestablished operations temporarily at the police academy, where Mayor Giuliani gave many press conferences throughout the afternoon and evening of September 11. By Friday, rescue and reliefs were organized and administered from Pier 92 on the Hudson River. Volunteers quickly descended on Ground Zero to help in the rescue and recovery efforts. At Jacob Javits Convention Center, thousands showed up to offer help, where they registered with authorities. Construction projects around the city came to a halt, as workers walked off the jobs to help at Ground Zero. Ironworkers, welders, steel burners, and others with such skills were in high demand. By the end of the first week, over one thousand ironworkers from across North America had arrived to help, along with countless others. The New York City Department of Design & Construction oversaw the recovery efforts. Beginning on September 12, the Structural Engineers Association of New York (SEAoNY) became involved in the recovery efforts, bringing in experts to review the stability of the rubble, evaluate safety of hundreds of buildings near the site, and designing support for the cranes brought in to clear the debris. The City of New York hired the engineering firm, LZA-Thornton Tomasetti, to oversee the structural engineering operations at the site. To make the effort more manageable, the World Trade Center site was divided into four quadrants or zones. Each zone was assigned a lead contractor, and a team of three structural engineers, subcontractors, and rescue workers. AMEC – North Tower along West Street Bovis Lend Lease – South Tower along Liberty Street Tully Construction Company, Inc. – Eastern portion of the WTC site Turner/Plaza Construction Joint Venture – Northern portion and 7 World Trade Center The Federal Emergency Management Agency (FEMA), the United States Army Corps of Engineers, the Occupational Safety and Health Administration (OSHA), and the New York City Office of Emergency Management (OEM) provided support. Forestry incident management teams (IMTs) also provided