Rainwater poured into the Kohl's at Hamburg on Wednesday night after an S-shaped section of drainage pipe near the roof disconnected, a Lexington firefighter said.
No one was injured, but the clothing store was closed as cleanup began. It was unclear whether the store would reopen Thursday.
The initial call was dispatched as a possible lightning strike, but firefighters determined that a 6-inch roof drain could not handle the amount of water dumped by a sudden thunderstorm around 7 p.m.
"The elbow of that pipe, as it came down through the ceiling, broke off the assembly and basically created a 6-inch hole in the roof," fire department Maj. Matt Galati said. "It created one significant water situation inside the store."
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Firefighters plugged the drain by jamming an inverted traffic cone into the hole, Galati said.
"It's probably going to be a 15- or 20-minute fix for a plumber, but it's going to be quite a water cleanup," he said.
The water leaked into the menswear section of the store, and there was an inch of water on the floor; some clothing was damaged as well, Galati said.