New York (AP) Relatives of victims killed at the World Trade Center have observed a moment of silence to mark the seventh anniversary of the September 11th terrorist attacks.
The silence marked the exact time - 8:46am - when the first hijacked plane struck the trade center, and then when the second plane hit minutes later.
Other ceremonies are being held throughout the day, including one at the Pentagon, where a new memorial will be dedicated. Services will also be held in Shanksville, Pa., where one of the hijacked planes crashed.
Later Thursday, Barack Obama and John McCain are due at ground zero to pay silent respects.