At the time of the terrorist attacks 10 years ago, Hahn was in his fifth grade class, at Jericho Elementary School, and remembers a teacher coming in and taking a few pupils to the office.
"These were kids of family members, I believe, who may have been working in the twin towers," he said.
"School ended early for us that day. I went home. It's also the day that's my father's birthday. I found my dad sitting on the chair in our living room watching the TV, just very upset."
Hahn (20), a geology major at Northwestern University, Chicago, said as he was pretty young at the time, he did not fully comprehend what was happening.
"I had one friend whose father worked in the towers and was very fortunate that he wasn't able to make it to work that day, for some reason or another. So his life was saved."
Hahn's father, Michael, a stock trader, was fortunate to have been working in an office on Long Island, and was lucky to have escaped the chaos that ensued in New York that day.
"It's interesting for my dad because it's his birthday, so every year now it's like it's a memorial day."
The aftermath from the 9/11 attacks is still felt throughout the United States, and Hahn notices it most when travelling.
"It's pretty big at times when we go to travel," he said.
"Levels of security have risen greatly. People are not as worry-free as they once were. I think this really opened a lot of peoples' eyes to what can take place in society regarding terrorist activity.
"My family, we used to travel around a bit. It's almost become more of a hassle going through airport security."
Hahn came to New Zealand because he wanted to go somewhere he could combine his study with good surfing.
"This place [Dunedin] is absolutely perfect for that," he said Hahn, who is at the University of Otago until December, completed his first marathon in 4hr 26min 18sec.
