Police officer Ryan Nash was responding to a call at high school not far from the World Trade Centre when someone reported an accident on the bike path outside.
Nash raced to a gruesome sight: A man in a truck had slammed into a school bus after mowing down people in a bike lane.
He was waving guns around and yelling.
The 28-year-old officer told him to drop the weapons and then fired once, striking the man.
Nash stopped the attacker, Sayfullo Saipov, in his tracks, but the officer is too modest to admit he's a hero, officials said.
"He was a hero," said Governor Andre Cuomo. "And the NYPD is not just the leadership, it's the men and women who are out there every day who are on the first line, and I think officer Nash really showed how important they are and how talented and how brave."
Saipov was actually wielding a pellet gun and a paintball gun, authorities said, but they looked like real guns.
Mayor Bill de Blasio and other civic leaders commended Nash for his cool head - and said he was a humble officer who felt like he was just doing his job.
Nash was taken to the hospital for a ringing in the ears and met with Police Commissioner James O'Neill.
"In a typical fashion of an NYPD cop, he thinks what he did was not an act of heroism," O'Neill said. "He thinks it's ... why he joined the police department."
