BOISE, Idaho (AP) -- An Idaho family has sued the U.S. Forest Service demanding more than $1 million after a large dead tree at a remote campsite fell and injured their young son.

Richard and Melinda Armstrong, of Caldwell, said their family was camping in the Boise National Forest in September 2010 when a gust of wind blew over the dead tree. It fell on their son, resulting in a large laceration, a compound fracture and a puncture wound in his back that impaired his breathing.

The boy, who was 6 at the time, was taken by helicopter to a hospital in Boise.

The couple said the Forest Service was negligent because it didn't remove the tree, which was a hazard. They're suing for more than $1 million in damages and emotional stress in federal court.

"The tree was clearly dead — had been dead for years — and was within eight feet of the fire ring, and within 48 feet of the Forest Service road," said Eric Rossman, their attorney in Boise, on Wednesday. "It was an obvious hazard."

Rossman said the Armstrong's son has undergone multiple surgeries and suffered "severe permanent impairment" of his leg.

The U.S. Forest Service didn't immediately return a phone call seeking comment on Wednesday.

At issue is whether the federal agency had a responsibility to ensure that a site where people frequented and was near a public road was adequately protected from a potentially dangerous tree.

There have been similar lawsuits elsewhere, including an Oregon man who sued the Forest Service in 2010 after he was struck and injured by a tree while driving in his truck. That case was settled earlier this year and has been dismissed.

The Armstrongs' camping trip took them about 50 miles north of Boise, to a remote Forest Service road east of the hamlet of Ola in Gem County. They contend the place along Squaw Creek where they were overnighting was, in fact, a developed campsite, according to the Forest Service's definition.

But even if the campsite was not considered to be developed, according to their complaint, the improvements there, including a fire ring made of rocks, and the Forest Service's knowledge that it was a place where people camped regularly created a duty for the agency "to take immediate measures to inspect and remove the tree, close the site and/or warn user at the site of the serious risk of injury, death or property damage."