A disaster

There are natural disasters, but also human disaster.
The September 11, 2001, at 9:00 am, a plane crashes into the World Trade Center, after a few minutes, another plane crashes into the other world trade center.
Nobody knows what happens and suddenly one of the towers falling and minutes later the other tower also falls, smoke invades the city and the ruins of the towers kill thousands of people.
This is a human disaster because it did Al Qaeda, a terrorist group.