A number of Hollywood celebrities and public figures have taken to social media to remember the lives lost in the U.S. terrorist attack to mark 20th anniversary.

• Sep 13, 2021

AceShowbiz - Mariah Carey, Questlove, and Octavia Spencer were among the stars remembering those who lost their lives in the 9/11 terrorist attacks on America on the 20th anniversary of the tragedy.

Celebrities and world leaders all took to social media on Saturday to honour the fallen with painful memories and heartfelt thoughts for the families of those who perished - particularly the people who died in the rubble of the World Trade Center.

Carey tweeted, "On this anniversary of 9/11, I find myself remembering the shock and anguish we all experienced with painfully deep sadness. Vivid images of the skyline I grew up loving so much, suddenly changed forever."

Questlove recalled the chaos in New York City the day before the terrorist attacks, revealing he lived "across the street from WTC for a decade+".

"It was a combo (combination) of MJ's (Michael Jackson) 30th concert + fashion week + Bono's RED charity launch with an all star marathon recording of 'What's Goin On' + the leftover MTV awards situation. even #GNR took up space w (with) their tour. Hectic was putting it light. This was chaos."

"The Roots' hotels got lost in the sauce. So now impatience, cussin, tears, anger... stuff I never did. Almost overdid it. I almost literally took it out on myself. The Soho Grand accidentally (or purposely cause of an MTV award call?) gave our rooms to another band."

He eventually found a room at the World Trade Center Marriott and had to wait 45 mins "while the system refreshes so they can find my room."

"I turned into the worst version of myself," Questlove recalls on Instagram. "I'm goin home, how bout y'all find another drummer to do this show."

"Entitlement right? We are supposed to be a**holes... right? my actions won't have consequences in the future, right? Clearly this is how the successful operate & win... right? Out the blue 3 rooms opened up at Bryant Park & now at 3am we are leaving. Next day nothing was the same."

The Roots drummer adds, "What's even CRAZIER?!?!?!? - finding out 20 yrs later Riq (Gees) & I were supposed to have a breakfast meeting w (with) our manager in WTC 9am. Listen to the universe people."

Oscar winner Spencer also took to Instagram to share what she was doing on the day of the tragedy, recalling, "20 years ago I was excited because I was guest starring on the sitcom Titus. I was up early running lines when my youngest sister called and said, 'turn on your tv, we are under attack.' I put on the Today show just as the first plane hit the tower. I called all of my LA friends and we watched in horror. I will never forget and mourn the loss of so many lives."

There were also photo tributes and heartfelt messages from former U.S. leader Barack Obama and his wife Michelle, British Prime Minister Boris Johnson, the royal family, Reese Witherspoon, Blake Shelton, Bruce Springsteen, Mark Hamill, Mark Wahlberg, U2, Spike Lee, and actor Steve Buscemi, who opened up about the post-traumatic stress disorder he experienced from volunteering with the New York Fire Department during the 9/11 terrorist attacks.

The 63-year-old "Reservoir Dogs" star was a member of Engine Company No. 55 in Manhattan's Little Italy neighbourhood from 1980 to 1984 and when planes crashed into the World Trade Center in 2001, he became a first responder, helping to search for survivors at Ground Zero.

"I still had my turnout coat and my helmet, and I just grabbed those things," he told Marc Maron's WTF podcast. "I was driven into the site that day. Walked around for hours and then found my company, found Engine 55 working there, and asked them if I could join them. I could tell they were a little suspicious at first, like, 'What are you doing here?' But I worked with them that day."

In an op-ed for Time magazine, he added, "(I) found a place on a bucket brigade. Instead of water going up, it was rubble coming down. Once in a while a body bag was passed, though none weighed much at all. That was disturbing. The dust? It was more of a nuisance: pulverized concrete and who-knows-what that clogged a face mask, so fast you worked better without one. Somebody'd say, 'This is probably going to kill us in 20 years.' "

"I haven't experienced any health issues, and I get myself checked out - but definitely, post-traumatic stress, absolutely. I was only there for, like, five days. But when I stopped going and sort of tried to just live my life again, it was really, really hard. I was depressed. I was anxious. I couldn't make a simple decision. It's still with me. It's still, you know, like there are times when I talk about 9/11 and I feel myself and I'm just right back there. I just, I start to get choked up and I realize, 'Ah, this is still a big part of me.' "