ASHLAND – Even as residents of the St. John Valley were cleaning up debris left over from severe thunderstorms that passed through Aroostook County on Sunday night, firefighters in three Maine counties were fighting at least 12 fires started by lightning from those storms.

Jim Downie, spokesman for the Maine Forest Service, said Wednesday that over a two-day period, firefighters had responded to 22 fires, mostly in Aroostook, Penobscot and Piscataquis counties.

As of Wednesday, 12 of those fires were still burning. They ranged in size from small spot fires up to six acres.

The fire danger across most of the state ranged from high to very high.

The largest fire was in Township 3 Range 7 at Deasey Mountain, west of Stacyville in northern Penobscot County. That fire, which was spotted late Tuesday, had burned about six acres as of Wednesday, according to Russ Beauchemin, regional ranger for the Maine Forest Service Northern Region based in Ashland.

Beauchemin said about 20 firefighters, including the East Branch Hotshots, a specialized group of firefighters based in Island Falls, and some Irving Woodlands personnel were working on that fire.

He said the terrain was very steep and because of that, mechanized equipment could not be brought in. Two Forest Service helicopters were used Tuesday night and Wednesday to make water drops on the fire.

Without mechanized equipment, firefighters had to stretch about 7,000 feet of hose to fight the fire, Beauchemin said.

Another large fire near Elephant Mountain east of Greenville was proving to be “really stubborn,” Downey said. Like the Deasey Mountain fire, the terrain was very rugged and steep, and firefighters were unable to use mechanized equipment, Downie said.

In Aroostook County, a fire in Township 8 Range 11 near eastern Haymock Mountain had burned about 2 acres as of Wednesday.

“We fully expect to find more,” Downie said, noting that the fires were caused mostly by so-called dry lightning, a term used to describe storms where lightning was not accompanied by rain.

He said humidity that had been present earlier in the week had helped keep those fires from flaring up. Once the humidity was gone, conditions improved enough for the fires to go from a smoldering phase to open flame.