September 11 commemoration starts
The annual September 11 commemoration ceremony in the US has started with the tolling of a bell and a moment of silence.
The private anniversary ceremony is being held at the National September 11 Memorial & Museum plaza today in New York.
The tribute has centred on reading the names of the nearly 3,000 people killed in New York, at the Pentagon and near Shanksville, Pennsylvania, in the 2001 attacks, as well as recognising the six people killed in the 1993 trade centre bombing.
Families started to read the names of the deceased, pausing during the roll call only four times: to mark the times when the first plane struck the World Trade Centre, when the second plane struck, when the first tower fell and when the second tower fell.
President Barack Obama, on the morning after announcing a stepped-up offensive against the Islamic State militant group, observed a moment of silence to mark the anniversary.
President Obama, first lady Michelle Obama, vice president Joe Biden and scores of White House staff gathered solemnly under partly cloudy skies on the South Lawn of the White House and heard the playing of Taps, in what has become an annual observance.
The Obamas then will head to the Pentagon Memorial to attend a September 11 observance ceremony.