The 69-year-old Republican front-runner made the blunder while campaigning on the eve of the high-stakes presidential primary here by getting the date of the World Trade Center attacks in 2001.
"I wrote this out, and it's very close to my heart," he said at the outset of his remarks yesterday.
"Because I was down there and I watched our police and our firemen down at 7/11, down at the World Trade Center right after it came down. And I saw the greatest people I've ever seen in action," he said at a campaign rally at the First Niagara Center in downtown Buffalo.
The slip of the tongue could prove embarrassing for Trump as he has repeatedly mentioned the terror attacks while campaigning across New York, his home state, some reports said.
More From This Section
Trump has held up New York city's response to the September 11, 2001 terrorist attacks as a defining "New York value."
That's the phrase used disparagingly by Texas Senator Ted Cruz several months ago, which Trump has tried to turn on his Republican rival, CNN reported.
During his speech, Trump told supporters that "no New Yorker" could vote for his rival Cruz, as he did not represent what the state needs.
In the run-up to primary, Trump was widely predicted to win comfortably during the contest in New York, which has 95 Republican delegates up for grabs.