NASHUA — A three-alarm fire ravaged an upscale Nashua home Wednesday, sending two firefighters to the hospital with heat exhaustion.

“It had a good head start on us,” Deputy Fire Chief Dan Cronin said as he stood in the driveway of the home on 6 Jenny Hill Lane. “It had been going for a while.”

No one was home at the time of the fire, which may have been sparked by lightning from a fast-moving storm Wednesday afternoon.

Cronin said the fire was burning in the basement and first floor and making its way to the second floor when firefighters arrived. The call came in at 1:41 p.m.

Cronin said with no hydrants in the area, firefighters relied on Dunstable, Mass., fire engines to supply water.

Fire crews from Tyngsboro, Mass., and Londonderry were also dispatched to the scene.

Asked the extent of the damage, Cronin said: “I don’t know if its total, but it’s pretty extensive throughout.”

Mendel Mangel, who rents the house with colleague Eli Posner, stood outside the burned-out property Wednesday, assuming he’d lost everything he owned.

He said he suspected lightning was responsible for the fire. Though the cause of the fire is still under investigation, Cronin said lightning from Wednesday’s storm and dry conditions had the department busy throughout the day.

Cronin said both firefighters were in good condition. One even returned to the scene.

“These guys take a beating going in there,” he said.

- - - - - - - -