How was part of the Pentagon destroyed

American Airlines Flight 77 crashed into the Pentagon after departing from Dulles International Airport bound for Los Angeles. It got hijacked.

On the same day as 9/11, a bunch of jackwagons decided that they should run a plane into the pentagon after the twin towers were in shards.

Explanation:

Luckily the whole pentagon wasn't in pieces but left 125 people dead and 26 first-floor cement pillars were demolished.