On the 20th anniversary of Sept. 11th, 2001, notable figures both in the U.S. and across the globe are remembering the 2,977 people who lost their lives, as well as the first-responders and all the families affected by the attacks.

Joe Biden, Barack Obama, and Bill Clinton, as well as their wives, Jill, Michelle, and Hillary, were among those who gathered at the World Trade Center memorial, along with hundreds of other Americans, many of whom were holding photos of loved ones lost on that day.

“Twenty years ago, nearly 3,000 lives were cut short by an unspeakable act of cowardice and hatred on 9/11,” Biden, who was a senator at the time of the attacks, said in a statement. “As a nation, we must never forget those we lost during one of the darkest moments in our history and the enduring pain of their families and loved ones.”

While Biden himself didn’t make a speech, Vice President Kamala Harris spoke at the Flight 93 National Memorial in Shanksville, Pennsylvania. Former President George W. Bush also spoke in Shanksville, nhotably calling out domestic terrorism in his speech. 

”We have seen growing evidence that the dangers to our country can come, not only across borders, but from violence that gathers within,” Bush said. “There is little cultural overlaps between violent extremists abroad and violent extremists at home … they are children of the same foul spirit, and it is our continuing duty to confront them.”

The tributes and remembrances also came from Hollywood, with Mariah Carey writing that she finds herself “remembering the shock and anguish we all experienced with painfully deep sadness.” Jennifer Hudson asked her fans to join her in “praying for the loved ones of all those we lost.”

Check out more 9/11 commemorations below.