NEW YORK: The United States on Sunday commemorated the 15th anniversary of the 9/11 attacks with a moment of silence observed in a sombre remembrance service at Ground Zero in New York – where nearly 3,000 people were killed. US presidential candidates Hillary Clinton and Donald Trump temporarily ‘paused’ their bitter election campaign to attend the service with police and relatives of the victims at the September 11 memorial. The moments of silence was observed at the time when the first hijacked passenger jet hit the North Tower of the World Trade Centre. It was the first of six moments of silence that will be observed in the Big Apple. Ceremonies were also planned at the Pentagon – where another jet struck.