On the 25th anniversary of the Sept. 11 attacks, a South Tower survivor is sharing his story of escape, loss and resilience with CityNews — a detailed, harrowing account of what unfolded inside the World Trade Center as the deadliest terror attack in modern history began.Joseph Dittmar, then a commercial underwriting executive from Chicago, says he was on the 105th floor of the South Tower for a morning meeting when the first plane struck the North Tower at 8:46 a.m. He was one of 54 people inside a windowless conference room when the lights flickered — the only sign something catastrophic had happened.“We couldn’t see anything. We didn’t hear anything. We didn’t feel anything — just that flicker of lights,” Dittmar said in an interview with CityNews.A volunteer fire marshal entered the room and ordered everyone to evacuate. Dittmar was the last person out.“Fifty-four of us all said the same thing. ‘We’re fine, it’s New York. Stuff happens, don’t worry about it. Let us have our meeting.’ This gentleman was firm and said, ‘Listen, I am a volunteer fire marshal… I can’t leave until all of you leave, and I want to leave.'”Photo courtesy: The Associated Press.‘We didn’t have a clue’ — the descent beginsDittmar says the group was directed to walk down 105 flights of stairs. Cell phones showed no service — the main tower for southern Manhattan was atop the North Tower, already burning.As they descended, Dittmar said they had no understanding of the scale of the attack.“All of you knew way more of what was going on than any of us that were right there. We didn’t have a clue.”On the 90th floor, the stairwell door was propped open. Against fire‑safety training, Dittmar followed others out — and saw the North Tower for the first time.“Gaping black holes… flames redder than any red I had ever seen… pieces of the fuselage lodged inside the building,” Dittmar explained, telling CityNews he watched furniture, paper and even people being pulled out of the tower.“My first thought was, ‘My God, how did the pilot not see this building?’ He didn’t miss. He did exactly what he intended on doing. An unbelievable, gruesome sight.”Terrified, he returned to the stairwell.“I got to tell you, the first reaction? I was so afraid, so afraid,” Dittmar said. “I didn’t know what I was looking at, but all I did know was that I wanted to get home. I didn’t want to be there. I wanted to get home.”Photo courtesy: The Associated Press.The second plane hits the South TowerDittmar reached the 78th‑floor sky lobby, where many evacuees were choosing elevators. He stayed in the stairwell — a decision he says saved his life.He was between floors 74 and 72 when the second plane struck the South Tower at 9:03 a.m.“Never felt anything like that in my life. The stairwell was shaking violently… handrails breaking… concrete spidering… steps undulating like waves,” he said.A “heat ball” blew past him. Jet fuel filled the air.“Ignorance was bliss. We didn’t know a plane had gone through our building.”Related:9/11 anniversary a reminder of powerful bond between Canada, U.S. amid deteriorating relationshipStill, evacuees continued downward, helping those with injuries or mobility challenges. When Dittmar reached the lobby, he saw twisted steel, crumbled concrete and red markings on the ground.Security staff directed evacuees into the underground concourse because debris — and bodies — were falling outside.“I’ve never seen such an outpouring of caring and love… firefighters, paramedics, cops everywhere,” he shared.Eight blocks north, they heard the South Tower collapse.“You hear this unmistakable sound of twisting steel and crumbling concrete, and this would sound like a freight train just coming at us. That was the South Tower coming to the ground,” Dittmar shared. “And even more hauntingly, at that same time, the sound of tens of thousands of people on the streets of New York, all screaming the same blood-curdling scream, all at the same time.”Hours later, watching TV coverage, Dittmar saw the replay of the plane hitting his tower.“My God, how did I even get out of there? I almost fell to my knees when I saw that because I couldn’t get over the fact that that’s just where I was.”The razor‑thin margins of survivalDittmar says one colleague from the same meeting died after briefly stopping at a restroom on the 90th floor.“I had a friend of mine on [floor] 90 who was in the same meeting as me, who came out of the fire stairwell with me, and he looked at me, and he saw me getting ready to get back into the fire stairwell, and he said, ‘What are you going to do, Joe? And I said, ‘I’m getting out. I said, ‘What are you going to do, Lud? And Lud looked at me, and he said, ‘Yeah, I’m going to go, but before I go, I’m going to go, and he pointed to the nearest restroom,” Dittmar recounted.“That delay and his exiting cost him his life that day. The margins were razor-thin, razor-thin.”He credits critical decisions, luck and what he calls “divine providence.”Dittmar says he remains deeply grateful for Canada’s response — from first responders who travelled to New York to the now‑famous Gander story, where thousands of stranded passengers were sheltered for days.“Every ounce of help we got from Canada was greatly appreciated. We can’t have greater friends.”He also expressed gratitude to Canadian soldiers who served — and died — in Afghanistan following the attacks.“Those who served helped make the world a little bit safer. Their efforts were not in vain.”