Security guard saved 6 people on 9/11; 25 years later, they are trying to save him

When the World Trade Center was engulfed in smoke and flames on September 11, 2001, a security guard carrying a flashlight and bullhorn appeared to six people who were struggling to find a way out of the South Tower. He was Dereck Lovell, who was filling in that day and had never previously worked on their floor. Lovell guided the group towards a functioning staircase, helping them escape from a building that would collapse minutes later. Nearly 25 years on, the man those survivors credit with saving their lives is facing a different fight. In interviews with PEOPLE, Doug Brown recalled how Lovell helped the group escape, while Lovell revealed that he is battling kidney cancer and now needs a transplant.A chance assignment on a day that changed everythingLovell, now 68, was working as a security guard at the World Trade Center on September 11, 2001.