COLORADO SPRINGS, Colorado (AP) — President Joe Biden fell on stage at the US Air Force Academy graduation Thursday and the White House said he was “fine” after tripping over a sandbag.

Biden had been greeting the graduates in Colorado Springs, Colorado, at the front of the stage with salutes and handshakes, and turned to jog back toward his seat when he fell. He was helped up by an Air Force officer as well as two members of his US Secret Service detail.

Onlookers, including some members of the official delegation on stage, watched in concern before Biden, who at age 80 is the oldest president in US history, returned to his seat to view the end of the ceremony.

“He’s fine,” tweeted White House communications director Ben LaBolt. “There was a sandbag on stage while he was shaking hands.” Two small black sandbags were on stage supporting the teleprompter used by Biden and other speakers.

Biden has been dogged by questions about his age and his fitness to serve, and his missteps have become fodder for political rivals as he campaigns for a second term in 2024. He has stumbled before going up the stairs and onto Air Force One and he once got caught up in his bike pedals while stopping to talk to reporters near his home in Rehoboth Beach, Delaware.

Biden’s personal doctor said after the president’s most recent physical exam in February that Biden “remains a healthy, vigorous 80-year-old male, who is fit to successfully execute the duties of the Presidency.” Dr Kevin O’Connor also documented the president's stiffened gait, which O'Connor said was the result of spinal arthritis, a previously broken foot and neuropathy in the Biden's feet.

Biden is far from the first national political figure to stumble in public.

President Gerald Ford fell down while walking off Air Force One in 1975. GOP Senator Bob Dole of Kansas, the GOP presidential nominee at the time, fell off the stage at a campaign rally in 1996. President Barack Obama tripped walking up the stairs to a stage at a 2012 event. “I was so fired up, I missed a stair” he told the crowd.

President Donald Trump's gingerly walk down a ramp at the 2020 West Point commencement also sparked concerns about his health.

Trump, 76, was campaigning in Iowa when he heard about Biden's stumble and alluded to his own episode.

“He actually fell down? Well I hope he wasn’t hurt,” Trump said after an audience member told him about what had happened to Biden. “The whole thing is crazy. You gotta be careful about that ... 'cause you don’t want that, even if you have to tiptoe down a ramp.”