After months of public relations work to rebut lingering rumors of serious health problems, a medical episode which forced Hillary Clinton to be evacuated during a memorial event marking the 15th anniversary of the 9/11 attacks has reignited speculation regarding the former Secretary of State’s physical condition.

At roughly 9:30 a.m. local time, Mrs. Clinton was abruptly removed from the memorial event in Manhattan after suffering what senior law enforcement officials described as a “medical episode”, saying the former First Lady had apparently fainted.

Fox News, which broke the story, reported that a law enforcement official who witnessed the incident claims Mrs. Clinton’s “knees buckled” and required the assistance of two aides to enter a campaign van. The official added that Clinton lost a shoe while entering the vehicle.

Video from the evacuation has emerged, showing what appears to be Mrs. Clinton stumbling as two men help her into the van.

According to a statement released by campaign spokesperson Nick Merrill, Mrs. Clinton was “overheated” during the ceremony and went to her daughter’s apartment to recuperate. She briefly appeared in front of reporters some two hours later, saying she was “feeling great”.

Prior to Sunday’s incident, the Clinton campaign has played down her December 2012 concussion and lengthy recovery, while ridiculing rumors she is suffering from significant physical ailments.

But critics have pounced upon what they claim is evidence of chronic weakness in the Democratic nominee, including a February 2016 photograph of Mrs. Clinton relying on two aides to help her up stairs during a visit in South Carolina.

Social media lit up Sunday following Clinton’s “medical episode” with renewed speculation that the former Secretary of State is concealing her poor health, despite being rebuffed by Mrs. Clinton’s personal physician.