In a shocking new development regarding Tuesday's brazen terror attack on an upscale hotel in Kenya's capital of Nairobi which left 15 dead as Somali-based al-Shabab militants stormed through the complex with automatic weapons, the lone American citizen identified among the dead was a 9/11 survivor.

Image via AP/FOX

The victim, Jason Spindler, was confirmed by family members to have survived the terror attacks in New York City on Sept. 11, 2001. “It is with a heavy heart that I have to report that my brother Jason Spindler passed away this morning during a terror attack in Nairobi, Kenya. Jason was a survivor of 9-11 and a fighter. I am sure he gave them hell!”, his brother Jonathan posted on Facebook.

Described further as managing director of an investment firm that attempts to grow small businesses in emerging markets such as Africa, Jason Spindler was one of 15 killed after four gunmen from the al-Qaeda affiliate al-Shabab militia stormed a Riverside luxury hotel in a posh area of Nairobi.

Jason Spindler, image source: I-Dev International/ Facebook

Government troops and police responded in what ended up being a 20-hour siege and shootout between up to five terrorists and security forces.

The Kenyan president later announced the terrorists were killed, with two others thought to be involved under arrest after hideouts were raided.

The Daily Beast, citing other reports, notes that on 9/11 Spindler had been working inside the World Trade Center’s Building 7 before it was evacuated and collapsed:

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

Most of the American public to this day remains unfamiliar with the Building 7 collapse — which occurred at free fall speed — though it was never directly hit by an incoming plane, but suffered fire and debris damage as a result of the attacks on the neighboring Twin Towers, for which it's remained subject of fierce controversy and speculation.

Spindler was the CEO of an investment firm, I-Dev International, which he founded and managed. Among the dead was also a British national, which was announced by the foreign office.

Image of civilians escaping the attack scene as it unfolded, via the AP.

Image via the AP

Parts of Tuesday's terror assault were captured on CCTV footage. The attack reportedly involved an initial suicide bombing in the hotel lobby, as well as explosions of three vehicles on the complex, before attackers dressed in paramilitary fatigues went on a shooting rampage in the area.

Like the 2013 attack at the Westgate Mall which killed over 70 and wounded some 200 more, this terror event appeared aimed at wealthy Kenyans and foreigners.