Some witnesses near the World Trade Center feel the ground shaking just before the South Tower starts to collapse: 
EMT Joseph Fortis is heading across West Street, when, he says, “the ground started shaking like a train was coming.” He then looks up and sees the South Tower starting to collapse. [City of New York, 11/9/2001] Lonnie Penn, another EMT, is outside the Marriott Hotel, which is adjacent to the North Tower. He and his partner “felt the ground shake. You could see the towers sway and then it just came down.” [City of New York, 11/9/2001] Bradley Mann is at the EMS staging area on Vesey Street. He says, “Shortly before the first tower came down I remember feeling the ground shaking. I heard a terrible noise, and then debris just started flying everywhere.” [City of New York, 11/7/2001] Battalion Chief Brian O’Flaherty is walking into the lobby of the Marriott Hotel. He says, “I hear a noise. Right after that noise, you could feel the building start to shudder, tremble, under your feet.” He then hears the “terrible noise” of the South Tower collapsing. [City of New York, 1/9/2002] Witnesses will also notice the ground shaking before the North Tower collapses (see Shortly Before 10:28 a.m. September 11, 2001).
4:30 p.m. September 11, 2001: WTC Building 7 Area Is Evacuated due to Anticipated Collapse
According to numerous rescue and recovery workers, the area around World Trade Center Building 7 is evacuated at this time. [Kansas City Star, 3/28/2004] For example: Emergency medical technician Joseph Fortis says, “They pulled us all back at the time, almost about an hour before it, because they were sure—they knew it was going to come down, but they weren’t sure.” [City of New York, 11/9/2001] Firefighter Edward Kennedy says, “I remember [Chief Visconti] screaming about 7, No. 7, that they wanted everybody away from 7 because 7 was definitely going to collapse.” [City of New York, 1/17/2002] Firefighter Vincent Massa: “They were concerned about seven coming down, and they kept changing us, establishing a collapse zone and backing us up.” [City of New York, 12/4/2001] Firefighter Tiernach Cassidy: “[B]uilding seven was in eminent collapse. They blew the horns. They said everyone clear the area until we got that last civilian out.” [City of New York, 12/30/2001] Battalion Fire Chief John Norman: “I was detailed to make sure the collapse zone for 7 WTC had been set up and was being maintained.” [Fire Engineering, 10/2002]
Several New York Fire Department chief officers, who have surveyed Building 7, have apparently determined it is in danger of collapsing. [Fire Engineering, 9/2002] For example, Fire Chief Daniel Nigro explains their decision-making process, saying: “A number of fire officers and companies assessed the damage to the building. The appraisals indicated that the building’s integrity was in serious doubt. I issued the orders to pull back the firefighters and define the collapse zone.” [Fire Engineering, 9/2002] Fire Chief Frank Fellini says, “We were concerned that the fires on several floors and the missing steel would result in the building collapsing.” [City of New York, 12/3/2001] And Fire Captain Ray Goldbach says, “[W]e made a decision to take all of our units out of 7 World Trade Center because there was a potential for collapse.” [City of New York, 10/24/2001] However, some firefighters seem surprised at this decision. When Fire Commissioner Thomas Von Essen is making his way through hundreds of firefighters who are being held away from the WTC site, he hears complaints like, “It could take days for that building to come down,” and, “Why don’t they let us in there?” [Essen, 2002, pp. 45] When Deputy Fire Chief Nick Visconti is instructing firefighters to evacuate the area, one comment he receives is, “[O]h, that building is never coming down, that didn’t get hit by a plane, why isn’t somebody in there putting the fire out?” [Firehouse Magazine, 9/9/2002]
