A father was killed and his son severely injured when a tree toppled by a powerful storm fell on their tent in a northeastern Minnesota forest this weekend, according to sheriff's officials.

The father and teenage son were camping at Duncan Lake with another man and his son on Father's Day in the Boundary Waters Canoe Area Wilderness in the Superior National Forest about 10:30 p.m. Sunday when the storm began, according to the Cook County Sheriff's Office.

The two others were outside the tent when the tree came down as all four were getting ready to leave the campsite, Chief Deputy Will Sandstrom said. The storm's straight line winds snapped large trees in half, he said.

"As soon as the winds came up, they were trying to get to a safer area away from the trees," Sandstrom said.

The injured boy was taken to a hospital and then airlifted to Duluth; there was no immediate word on his condition. Because paramedics had to cross the lake to reach the campsite, authorities decided to retrieve the father's body on Monday.

A second emergency call at about the same time involved a man camping on Clove Lake who had also been injured by a falling tree, according to Cook County sheriff's officials. The man was taken to a hospital with injuries to his upper body; his condition was not immediately known.

In St. Louis County, three people with the outdoor education program Outward Bound were injured in an indirect lightning strike near Crooked Lake, according to the sheriff's department. The injuries included the temporary loss of consciousness and superficial burns, while another three people in the group complained of numbness. They were flown to a base in Ely, from which they were taken to the hospital.