Harlem residents were stunned and heartened Sunday by the news that someone among them may have woken up a multi-millionaire.

One of two winning Powerball tickets was sold at a bodega in West Harlem. The as-yet-unidentified winner will split the jackpot of nearly $688 million with a lucky counterpart who bought the other winning ticket in Iowa, lottery officials said. The winners matched all six numbers — 8, 12, 13, 19, 27 and Powerball 4 — to claim the fourth-largest lottery prize in United States history.

“Who was it?” asked Jose Espinosa from behind the counter at his father’s bodega, West Harlem Deli, where one of the tickets were sold. “That’s the only question I have.”

Mr. Espinosa, 41, said he was most likely the one who printed the winning ticket since he spends most of his waking hours working the counter at the deli, which his father has owned for more than 15 years.