11, 2001 5:30pm EDT
The first of the two towers fell shortly after 10 a.m.; the second crashed to the ground about a half hour later.
At about 5:25 p.m. Eastern time, Building 7, a building near the downed World Trade Center towers that housed the city's emergency response team among other things, collapsed as well. That building stood 47 stories tall.
As many as 50,000 people work in the World Trade Center. There has been no word yet on how many were killed in the attacks, but New York Mayor Rudolph Giuliani told ABC News "I wouldn't want to say what the death toll could be. It will be a horrible number. I saw people dropping out of windows."
A local eyewitness had a similar story.
"I looked outside and saw a big chunk of the World Trade Center missing," Ellen Leon, a Verizon employee, told Reuters. "Fifteen minutes later I saw people jumping out of the building. Bodies were flying out. I don't know if they were already dead or if they were just going to die."
New York's hospitals were overwhelmed with those suffering injuries from the attack. Giuliani said at least 2,100 people had been injured, with 600 of them taken to hospitals by mid-afternoon. Hospitals say those numbers will rise.
"Hundreds of people are burned from head to toe," Dr. Steven Stern at St. Vincent's Hospital in the Greenwich Village area of lower Manhattan told Reuters.
A thick cloud of smoke still hangs in the air around the rubble of the two buildings. Bridges and tunnels between New York and New Jersey have been closed.
Giuliani said New Yorkers should evacuate lower Manhattan. He said the mass transit authority would send subways into the area to help people leave and that ships have also been called in to assist with the evacuation.
The National Guard in New York has been placed on alert and the city's emergency management personnel have been called out to assist with rescue efforts.
The two crashes in New York were among four plane crashes this morning nationwide. One plane crashed into the Pentagon building outside Washington, the home of the U.S. armed forces. Another crashed in western Pennsylvania, near Pittsburgh.
Virginia congressman James Moran told the Associated Press the plane that crashed in Pennsylvania was intended for Camp David, the presidential retreat in Maryland. The crash site was 85 miles northwest of Camp David.
Speaking from Barksdale Air Force Base in Louisiana this afternoon, President Bush said the the United States "will hunt down and punish those responsible for these cowardly acts."
"We have taken all appropriate security precautions to protect the American people. Our military at home and around the world is on high-alert status and we have taken the necessary security precautions to continue the functions of your government," the president said.