It was awful to think that there had been 4 planes hijacked that day , and how it could get much , much worse . Later that night when I got home , I was glued to the TV .... watching in horror as the Twin Towers came down and all the rescue workers and other people who were trapped in the buildings as they fell . It all seemed so surreal . So , so sad . At that time they thought there may have been 50,000 people in the building , and so many people were missing .
According to the above context, answer the following question.
What happened after this event because of it ?


Airport security increased