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A grocery store employee in Massachusetts has become an online sensation after footage of his incredible singing voice went viral over the weekend.

Guilherme Assunção, a worker and deliveryman at Russo’s in Watertown, near Boston, treated customers to a beautiful, impromptu rendition of “O Holy Night” on Friday of last week — and locals can’t stop singing his praises.

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“I left my cart and left my bag, and people were circling around,” one shopper told The Boston Globe. “Everybody just stopped. It was just so beautiful.”

Assunção, who originally hails from Brazil, had been an aspiring singer before taking a job with the family-run Russo’s market. On Friday, however, he noticed that the owners of the shop were setting up sound equipment for a group of singers they had hired to sing this past weekend, and Assunção jumped at the chance to test out the microphone.

“People told me the whole store stopped — even the employees stopped to watch me,” Assunção, 23, told The Washington Post. “A lot of people were filming in front of me.”

The owners of the shop later uploaded the above footage to Facebook, where it’s been viewed more than 77,000 times. They also asked Guilherme, or “Gilly,” as they call him, to sing over the weekend with the professional carolers they had hired for Saturday and Sunday.

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Singing at Russo’s has also turned into something of a regular gig for Assunção, as the store has confirmed he’ll be back to sing this weekend.

Assunção moved from Brazil to Utah in 2015, with the intention to pursue his singing career and attend college. He later left Utah for Boston, where he found a job as a dishwasher at Russo’s, and enrolled himself in classes at the Computer Systems Institute, according to the Globe.

He’s never had any formal training, but he told the Post he starred in a hugely popular production of “The Phantom of the Opera” at his high school in Brazil, which played to nearly 5,000 people each night.

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Assunção still works in the hot food station of Russo’s, although he says he would ultimately love to study singing at Boston’s Berklee College of Music.

“For music, all you need is opportunities,” Assunção  told the Globe. “And I hope this helps to open some.”