It was the first official Defense news briefing after the incident.
Defense Secretary Donald H. Rumsfeld was in the Pentagon at the time of the crash, and he walked outside the building to investigate and offer help, Quigley said. The admiral noted that the injured had been taken "to a variety of area hospitals" and added that Pentagon officials are working to provide a list of injured.
"We will work our way through to identifying them and getting their names out to their loved ones," Quigley said.
The Pentagon incident followed two other alleged aerial hijackings that resulted in crashes that ultimately collapsed the 110-story twin towers of the World Trade Center in New York City.
Quigley said defense officials began to assemble a crisis action team after the second aircraft struck the World Trade Center.
"Shortly after that, the aircraft hit [the Pentagon]," he concluded.