America marks 20 years since the horror of 9/11 attacks

Observances are also planned at the two other sites where the 9/11 conspirators crashed the jets: the Pentagon, and a field near Shanksville, Pennsylvania

Former first lady Michelle Obama, President Joe Biden and first lady Jill Biden attend a ceremony marking the 20th anniversary of the September 11 attacks. Picture: AP

The September 11 anniversary commemoration at ground zero in New York City began with a tolling bell and a moment of silence, exactly 20 years since the start of the deadliest terror attack on US soil.

US president Joe Biden was joined by former presidents Barack Obama and Bill Clinton and a crowd of victims’ relatives and first responders for the ceremony at the 9/11 memorial plaza in the city.