Saturday was Lunar New Year, and people were gathered in Monterey Park, California – a majority Asian-American city.

But the revels were shattered after a 72-year-old gunman named Huu Can Tran opened fire, killing ten people and wounding ten others at the Star Ballroom Dance Studio, where he frequented.

Tran was gearing up for another round of violence at another dance studio when a heroic civilian disarmed him – and saved countless other lives.

That hero, 26-year-old Brandon Tsay, recounted the terrifying moments to GMA’s Robin Roberts.

Tsay described how he felt something come over him, wrestled the gun away, and then shouted for the attacker to “Go away, go! Get the hell out of here.”

Tsay says he expected the gunman to lunge for his weapon, but Tran just stood there contemplating whether or not to fight back. Tsay says Tran walked away.

Tsay seemed to demur when called a hero, describing courage as “not the absence of fear” but rather the ability to persevere when things get hairy.

In interviews, Brandon Tsay has described the decision to fight back as something primal – a decision beyond his logic. But he could tell that Tran meant to “do harm” – and he was right.

Tran later shot and killed himself after a traffic stop led to an armed stand-off with police. His motive remains a mystery.