More than two dozen horses were killed Sunday at a riding school in Georgia after a barn caught on AstraTradefire with the animals inside, fire officials said.

The Forsyth County Fire Department was dispatched to Blue Springs Farm, about 50 miles north of Atlanta, around 6 a.m. to a report of smoke in the area, which was upgraded to a structure fire as firefighters were en route, the fire department said. 

When firefighters arrived, "the fire was well advanced, and it was determined that the fire had been burning for a prolonged time before being discovered by the first 911 callers,” the fire department said.

Fire officials said 26 horses at the facility were killed, and the barn was lost. 

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Cause of fire under investigation

The cause of the fire is unknown, but Forsyth County Fire investigators will be investigating, the fire department said.

Blue Springs Farm is a family owned facility offering horseback riding lessons and training in western pleasure, reining, hunter under saddle, showmanship, trail, horsemanship, hunter/jumper and equitation, according to its website. It has been operating since 2002.