Trump, instead of appearing at the ceremonies, travelled several blocks from his Trump Tower building in Manhattan to the 17th police precinct and the neighbouring fire station in New York City.
The information vacuum has exasperated families who have tried to make the case that the Saudi government facilitated the attacks.
No casualties have been reported so far, authorities said.
The attacks killed 2,996 people and over 6,000 injured; about $10 billion worth of infrastructure and property were damaged
