Jay and Noah Oaks and a third brother, Mark, were working in the barn when lightning struck just outside the door.
"All of a sudden lightning cracked," Jay Oaks said. "It was 10 feet away from us."
Jay Oaks said he and his brothers saw burning hay and began removing it.
"We got down through the fire. ... About that time, it just exploded in our face," he said. "It happened so fast. ... We thought we had it."
"It was hot and loud, crazy," Noah Oaks said Friday night. "It was hotter than you could stand."
There were about 20 cows and calves inside the barn, Jay Oaks said. Five calves died in the fire.
Their mother, Evelyn Oaks, 62, watched as her barn burned.
"The barn is completely all gone," she said. "I guess all that's left is the silos.
"It went fast."
Evelyn Oaks said the portion of the barn that held the hay was two stories tall before the fire. By 4 p.m. it had been reduced to one story, with black, yellow and gray smoke billowing from the hay bales inside.
A cow-milking house and a supply room also were gutted by flame.
According to Washington County Emergency Services, more than 75 fire and rescue personnel arrived from about 15 companies in Washington County and Franklin County, Pa. The fire was under control at 5:40 p.m., but burned for more than an hour after that.
Firefighters pumped water from nearly a half-mile away, said Rick Rowe, deputy chief at Clear Spring Volunteer Fire Department.
There were periods when water hoses were slack as crews waited for water to begin flowing while flames continued to lick.
About an hour into the fire, Rowe said there finally was a stable water supply, but that left "the heat and just trying to keep these guys hydrated (and) lack of manpower" as problems.
The county's Emergency Rehab Unit and a separate mass-casualty unit were called to feed the firefighters and keep them supplied with drinking water or other supplies that might be needed for the heat.
"It's hot as heck," said Tom Wilkins, one of the firefighters with the Maugansville Goodwill Volunteer Fire Co. "I've lost track of time."
Evelyn Oaks said she was shaken by the fire.
"It's just one of those things that happen, I guess. I just hope everything works out," she said.
Noah Oaks said in retrospect that he wouldn't have acted differently.
"I still would have tried to save everything that I could," he said.