An American businessman who reportedly survived the 9/11 World Trade Centre terror attack in 2001 is among the 21 people killed Tuesday when militants stormed a hotel and office complex in Nairobi, Kenya.

Jason Spindler was the founder and CEO of the I-DEV International investment firm. He was having lunch at the targeted complex of the firm when the attack occurred, according to Spindler’s colleagues. The 40-year-old Houston native was working in Africa, using the San Francisco-based company he co-founded to bolster businesses in emerging markets. Reports cite that a British man and several Kenyans were also killed during the attack.

Jason Spindler’s brother Jonathan confirmed his death in a post on Facebook on Tuesday that read, “It’s with a heavy heart that I announce that my brother, Jason, passed away this morning during a terror attack in Nairobi. Jason was a survivor of 9/11 and a fighter. I am sure he gave them hell. There are no words to describe how our family is feeling but I can say... Jason Spindler, you are and always will be an amazing son, brother, and uncle. Rest in peace—we will miss you dearly.”

Al-Shabab, an Islamic extremist group allied with Al-Qaeda, claimed responsibility for the massacre at the hotel. The Somali group has allegedly targeted Kenya since it sent its army into Somalia in October 2011 to fight the jihadist group.

Spindler was reportedly working as an analyst in New York for the Salomon Brothers investment bank during the 9/11 attack and escaped with his life from the World Trade Center’s Building 7, which was completely destroyed after the collapse of the North Tower.