lobby of the North Tower. By 9:00 a.m., shortly before United Airlines Flight 175 hit the South Tower, the FDNY chief had arrived and took over command of the response operations. Due to falling debris and safety concerns, he moved the incident command center to a spot located across West Street, but numerous fire chiefs remained in the lobby which continued to serve as an operations post where alarms, elevators, communications systems, and other equipment were operated. The initial response by the FDNY was on rescue and evacuation of building occupants, which involved sending firefighters up to assist people that were trapped in elevators and elsewhere. Firefighters were also required to ensure all floors were completely evacuated. Numerous staging areas were set up near the World Trade Center, where responding fire units could report and get deployment instructions. However, many firefighters arrived at the World Trade Center without stopping at the staging areas, partly because at 8:48 a.m. Battalion 1 transmitted a Third Alarm and ordered third alarm units to the Staging Area and second alarm units to the Towers. As a result, many chiefs could not keep track of the whereabouts of their units. Numerous firefighters reported directly to the building lobbies and were ordered by those commanding the operating post to proceed into the building. Problems with radio communication caused commanders to lose contact with many of the firefighters who went into the buildings. The repeater system in the World Trade Center, which was required for portable radio signals to transmit reliably, was malfunctioning after the impact of the planes. As a result, firefighters were unable to report to commanders on their progress, and were unable to hear evacuation orders. In addition, many off-duty firefighters arrived to help without their radios. FDNY commanders lacked communication with the NYPD, who had helicopters at the scene, or with Emergency Medical Services (EMS) dispatchers. The firefighters on the scene also did not have access to television reports or other outside information, which could help in assessing the situation. When the South Tower collapsed at 9:59 a.m., firefighters in the North Tower were not aware of exactly what happened. The battalion chief in the North Tower lobby immediately issued an order over the radio for firefighters in the tower to evacuate, but many did not hear the order, due to the faulty radios. Because of this, 342 firefighters died in the collapse