Washington (CNN) -- A chunk of a Pentagon wall smashed by a plane hijacked by 9/11 terrorists was presented to the FBI's Washington field office Wednesday in recognition of its assistance.
During a military ceremony, the FBI received an 800-pound limestone block that was recovered from the west facade of the Pentagon and has been kept in storage for almost 10 years.
The head of the FBI's Washington office, assistant director James McJunkin, said the stone will be permanently displayed in the building's lobby "so that every visitor who enters this building, every employee who walks through these doors, and every agent assigned to this post will remember what happened on that horrific day, what the bureau did in response to that attack and the unending commitment we have to never letting it happen again."
McJunkin said FBI agents arrived at the Pentagon six minutes after the plane hit the building. "We found the scene reflected what America saw on their televisions that day: confusion, destruction, dread," he said. By day's end, the bureau had 700 agents and support staff on site who set up a security perimeter to guard against possible follow-up attacks. Agents then began to collect evidence while simultaneously respecting the remains of those who died. The evidence-gathering continued for three weeks.
Maj. Gen. Karl Horst, of the U.S. Army Military District of Washington, said FBI agents responded "with extraordinary heroism when -- without warning -- they were called upon to perform their duty in the midst of an unimaginable act of terrorism."
Horst and FBI officials said September 11 required law enforcement, the military, fire departments and medical teams to work closely together without regard for jurisdictional issues.
John Perren, one of the FBI officials who rushed to the scene, warned, "Al Qaeda will not go quietly, it is resilient, it adjusts its tactics." Perren led the local Joint Terrorism Task Force on September 11.
The military reserved two other 800-pound chunks of Pentagon wall, one for the Arlington County (Virginia) Fire Department, which responded to the Pentagon attack, and one for the New York City Fire Department.