BOISE, Idaho (AP) — Federal officials say they are not to blame for the crash of a small airplane at a backcountry Idaho airstrip that killed four men and are requesting that a lawsuit filed by family members be dismissed.

The U.S. Department of Justice in legal documents filed earlier this month in U.S. District Court says the U.S. Forest Service is not at fault for the crash in the Salmon-Challis National Forest.

John H. Short, Russell Taylor Cheney, Aaron J. Linnell and Andrew David Tyson died in the April 10, 2015, crash near Challis.

A complaint filed by family members of the four men says Forest Service workers failed to remove a 50-foot (15-meter) tree that the airplane collided with shortly after takeoff.