By Eun Kyung Kim, TODAY contributor

Character is what you do when no one is watching.

But a stranger was watching New York Police Officer Lawrence DePrimo when he decided to buy a barefoot homeless man a pair of new boots on a cold night earlier this month.  

"The two things that really stuck out in my mind that night was how cold it was and that this was the most polite gentleman I ever met, and I knew I had to help him," DePrimo said Friday on TODAY.

Unbeknownst to DePrimo, a nearby tourist snapped a picture of the random act of kindness — and the photo quickly went viral.

"I knew what I was looking at," said Jennifer Foster, who was visiting Times Square from Arizona. The daughter of a long-time Phoenix police officer, she realized she was witnessing something amazing and quickly grabbed her phone.

"I knew it was remarkable," she said.

Foster sent the photo to the New York Police Department, which posted the snapshot to its Facebook page and quickly picked up more than 430,000 likes. Mentions of the photo also started trending heavily on Twitter.

On TODAY's Facebook page, the photo has been liked by more than 70,000 followers

DePrimo, 25, was on counter terrorism patrol the night of  Nov. 14, when he spoke to the homeless man. He then went inside a nearby shoe store to purchase some socks and boots.

"I really didn't think about the money," he told TODAY's Savannah Guthrie. "I said, I don't care what the price is. We just got to help him out."