The Queen has sent a message to US President Biden this morning.
She says her thoughts and prayers are with the victims, survivors and their families, as well as the first responders and rescue workers.
In her message, she also paid tribute to the resilience of the communities who joined together to rebuild.
“My visit to the site of the World Trade Center in 2010 is held fast in my memory,” she says.
“It reminds me that as we honour those from many nations, faiths and backgrounds who lost their lives, we also pay tribute to the resilience and determination of the communities who joined together to rebuild.”
