Remembering attack on twin towers: Defining images from the 9/11 attacks

Today marks the day when terrorists hit the World Trade Centre in the US, killing and injuring several people in the building. Below are photos documenting the gruesome 2001 attack by AlQaeda which has remained fresh in the memories of US citizens and the world.

The second tower of the World Trade Center bursts into flames after being hit by a hijacked airplane in New York September 11, 2001.[Image: Reuters]

Pedestrians react to the World Trade Center collapse September 11, 2001. [Image: Reuters]

Then-President George W. Bush listens as White House Chief of Staff Andrew Card informs him of a second plane hitting the World Trade Center while Bush was conducting a reading seminar at the Emma E. Booker Elementary School in Sarasota, Florida, September 11, 2001. [Image: Reuters]

People look out of the burning North Tower of the World Trade Center in New York City September 11, 2001. [Image: Reuters]

A helicopter flies past the World Trade Center after a commercial plane slammed into it in New York City, September 11, 2001. [Reuters]

A rescue helicopter surveys damage to the Pentagon as firefighters battle flames after a hijacked airplane crashed into the U.S. military headquarters outside of Washington, September 11, 2001. [Image: Reuters]

The remaining tower of World Trade Center, Tower 2, dissolves in a cloud of dust and debris about a half hour after the first twin tower collapsed, September 11, 2001. [Image: Reuters]

Rescue workers carry mortally injured New York City Fire Department chaplain, the Rev. Mychal Judge, from the wreckage of the World Trade Center in New York City September 11, 2001. The chaplain was crushed to death by falling debris while giving a man last rites in the trade center. [Image: Reuters]

A man grieves outside the World Trade Center site in New York, September 11, 2006. [Image: Reuters]