Days of dry weather and Monday's windy conditions fueled several brush fires in the Slate Belt region.
The mountain near Wind Gap in Northampton County was on fire into the night. Local and state agencies stayed on scene overnight to make sure flames did not flare back up.
Tuesday, investigators will be looking into whether it was intentionally set.
Fire crews were able to make quick work of the flames on the Monroe County side, putting out the fire in the afternoon, but smoke smoldered all day on the Northampton County side. People below in Wind Gap watched nervously outside their doors.
"No rain. It's dry," Trudy Kleintop of Wind Gap said. "The wind doesn't help."
Kleintop lives about a mile below where the fires started. She said she watched the smoke move quickly over her town.