Terrorist attacks on the United States is the answer.
On September 11, 2001 that was the day New York got attacked by terrorists. The Twin Towers were the ones that got affected, 2,996 people (maybe more) died during that attacked. The terrorists were one of the 2,996 people that died (19 of them died). more than 6,000 were injured that day.
#NeverForget
Hope this helped
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