FDNY Emergency medical technicians (EMTs) and Paramedics, along with 9-1-1 system ambulances operated by voluntary hospitals and volunteer ambulance corps, began arriving at 8:53 a.m., and quickly set up a staging area outside the North Tower, at West Street, which was quickly moved over to the corner of Vesey and West Streets. As more providers responded to the scene, five triage areas were set up around the World Trade Center site. EMS chiefs experienced difficulties communicating via their radios, due to the overwhelming volume of radio traffic. At 9:45, an additional dispatch channel was set aside for use by chiefs and supervisors only, but many did not know about this and continued to operate on the other channel. The communication difficulties meant that commanders lacked good situational awareness.