Query: Which al-Qaeda cell were the 9/11 hijackers members of?
Context: Once the hijackers assumed control of the airliners, they told the passengers that they had the bomb on board and would spare the lives of passengers and crew once their demands were met – no passenger and crew actually suspected that they would use the airliners as suicide weapons since it had never happened before in history. The hijackers – members of al-Qaeda's Hamburg cell – intentionally crashed two airliners into the Twin Towers of the World Trade Center in New York City. Both buildings collapsed within two hours from fire damage related to the crashes, destroying nearby buildings and damaging others.