A teen cashier's act of kindness in South Dakota has gone viral, but he says he's no hero.

Levi Zimmerman, a high school student in Yankton, works part-time at Walmart as a cashier. On Wednesday, Josh Derickson posted an image of the young man on Facebook, saying that he witnessed Zimmerman pull out his own debit card to pay for an elderly couple's groceries when they came up short.

Other Walmart customers commented on the Facebook post, saying it's not the first time Zimmerman has helped a customer in need.

Zimmerman told KCAU that he's no hero, he's just doing what his parents taught him to do when he encounters people in need.