The 9/11 attacks of 2001 – in pictures

• This gallery contains sensitive images that some viewers may find distressing

Twenty-five years ago, as New Yorkers woke to crisp blue skies after a storm the day before, two planes - United Airlines Flight 11 and Flight 175 - were hijacked in Boston by terrorists loyal to the al-Qaida leader, Osama bin Laden. They were flown into the twin towers of the World Trade Center 17 minutes apart. On the same day American Airlines Flight 77 was flown in to the Pentagon in Virginia, and a fourth hijacked plane, United Airlines 93, was downed in Pennsylvania after a revolt by passengers. The attacks killed nearly 3,000 people