NEW YORK (CBSNewYork) – Two Con Edison workers were hurt when a manhole exploded in East Harlem.

The blast happened around 2:30 p.m. Saturday near the intersection of Second Avenue and 110th Street, just blocks away from an annual street festival.

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Surveillance video shows workers suddenly sprint away from the manhole, then rush back to steady a ladder, helping their colleagues escape the rising smoke, CBS2’s Reena Roy reported.

Officials said two Con Ed contractors suffered burns on their faces and were taken to Harlem Hospital.

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Roy spoke with people who heard a loud boom and then saw smoke. Meanwhile, others were enjoying the nearby Loiza Festival.

“It sounded like thunder, like a big thunder bolt. Then 30 minutes later, we came open and the lights sort of went out for a few seconds,” one man said. “It’s crazy, it’s scary. You know, you come into work, you don’t expect that.”

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Con Ed officials said they are working to figure out what caused the explosion.