Twenty-five years after September 11, Americans reflect on attack that changed a nation ↧ ↧ Twenty-five years after September 11, Americans reflect on attack t... Americans marked the 25th anniversary of the September 11 attacks on Friday with sorrow and ​somber reflection, honoring the nearly 3,000 people killed when hijacked planes slammed into the World Trade Center, the Pentagon and a Pennsylvania field in a shocking attack that reverberates to this day.