Danny Masterson's Cousin Among the 21 Dead at Terrorist Attack in Kenya

Danny Masterson is mourning the loss of his cousin, American businessman Jason Spindler, after he was killed in a terror attack on a Kenyan hotel compound.

Spindler, who would have turned 41 next week, was among the 21 dead at the hours-long attack at Nairobi's DusitD2 compound. Men armed with guns and explosives burst into the compound, Kenyan President Uhuru Kenyatta said.

Masterson took to social media to share his loss and condemn the actions of the terrorists who attacked the hotel.

"Scumbags known as Al-Shabaab attacked a hotel in Kenya as we all now know. They killed two dozen people including my/our cousin #JasonSpindler," The Ranch alum captioned an Instagram photo of the late Spindler.

"I know these cowards, who weren't already killed, will die slow painful deaths and we will dance on their graves," he wrote. "You disgrace Islam and you disgrace the beautiful people of the Muslim world. You justify your actions as holy but no Higher Being admits your existence. You are f—ing pieces of s—."

He finished with a note to Spindler: "Godspeed my Texas cuz. Your family will never be the same."

Spindler's parents told KTRK that he dedicated his life as a business investment adviser to helping others. He was the founder, CEO and managing director of I-DEV International, a strategy and investment advisory firm that attempts to grow businesses in emerging markets.

"We all miss him so much. And it's so sad that such a bright young person is taken away by terrorism," his mother, Sarah Spindler, told NBC News.

Nearly 18 years earlier, he worked at 7 World Trade Center in New York, and was late to work the morning of September 11 when the planes hit the towers. Sarah Spindler said he was emerging from the subway as the first tower fell.

Following his work in the World Trade Center, he joined the Peace Corps in northern Peru, where he helped farmers develop a co-op that would let them sell to larger markets. According to his biography on the company website, he led the growth of a $7 million locally owned agribusiness during his time in the Peace Corps.

A University of Texas at Austin business graduate, Spindler earned a doctoral law degree at New York University.

"His tragic death is a loss not only to his loved ones, but to the community of individuals dedicated to improving the lives of others through social enterprise," NYU said in a statement.

A Houston, Texas, native, Spindler was based out of San Fransisco, and for the last three years lived in Nairobi.

The siege on the hotel in Kenya ended Wednesday morning, Kenyatta told reporters. "The security operation at Dusit complex is over, and all the terrorists eliminated," he said, adding that more than 700 people were safely evacuated during the attack.

Surveillance footage shows the moment one of the attackers self-detonated a suicide vest in the foyer of the hotel, leaving behind billowing smoke as people fled. Before the explosion, another man walked by, stared at the attacker and kept walking.

At least 21 people have died in the attack, including 16 Kenyans, Spindler, one Briton and three unidentified people of African origin, CNN reports. Twenty-eight others have been hospitalized.

A State Department official described the attack at the upscale DusitD2 hotel as a "senseless act of violence," and condemned the assault. The American embassy in Nairobi is closely monitoring the attack, and State Department officials have offered assistance to local authorities.

Masterson was fired from Netflix's The Ranch in 2017 after several accusations of sexual assault surfaced against him. He has vehemently denied the accusations.