The Fire Department of New York (FDNY) and New York Police Department (NYPD) dispatch units to the World Trade Center within seconds of Flight 11's crash. On site, Port Authority Police Department (PAPD) officers begin evacuating the North Tower. PAPD headquarters in Jersey City, New Jersey dispatches additional officers from other command posts to the World Trade Center.

In July 2001, the Port Authority of New York and New Jersey, long-time managers of the World Trade Center, lease the buildings to real estate developer Larry Silverstein. On September 11, 2001, both Port Authority and Silverstein Properties staff are in the building working on the transition. With their expert knowledge of the towers, Port Authority fire safety, building and security staff help to coordinate the evacuation.1

1 “Emergency Services Mobilize” National September 11 Memorial & Museum n.d. Web. March 17, 2011
Courtesy of the National 9/11 Memorial and Museum