Remembrance services have been held in the United States to mark the eighth anniversary of the hijacked plane attacks of September 11, 2001.
More than 2700 people died when the four planes crashed in New York, at the Pentagon and in a field in Pennsylvania.
Thousands of people gathered on Friday in a square near the Ground Zero site in New York, where the twin towers of the World Trade Center were destroyed.
The names of the dead were read aloud at the services, taking almost an hour.
In Washington at the Pentagon, President Barack Obama said the years would not diminish the loss of that day and promised to maintain the pursuit of those responsible.
One hundred and eighty people died in the attack at the Pentagon.
A routine training exercise by the Coast Guard set off a security scare in Washington during the commemorations.
Despite early reports, officials in Washington say no shots were fired.
The Coastguard says the reports were based on radio calls made on an open training frequency, with people verbally simulating gunfire.
Departures from Washington National Airport were halted for about 20 minutes.