Strong winds and tornadoes ripped through much of northern Minnesota Sunday night, killing one camper in the Boundary Waters Canoe Area Wilderness and injuring others.

Hot and humid weather Sunday gave way to powerful storms in parts of Minnesota. A waiter at the Timberjack Smokehouse & Saloon in Pequot Lakes, Minn., found this hailstone. John Enger | MPR News

The man who died has been identified as Craig Walz, brother of Minnesota U.S. Rep. Tim Walz. He was killed while camping near Duncan Lake when heavy straight line winds downed a tree on his camp site.

His son Jacob was also severely injured.

"The family wants to express their profound gratitude to law enforcement, first responders and fellow campers who responded immediately to help," a spokesperson for Tim Walz said in a statement. "The family is also grateful for the messages of support and prayers they have received. They are devastated by the loss and ask for privacy at this time."

Craig Walz was an excellent chemistry and geometry teacher at St. Charles High School in southern Minnesota, said Ben Bernard, the school's principal. "He'll be missed," Bernard said.

"The thoughts and prayers of all of us at the Minnesota DFL are with Craig's wife Julie, his daughter Avery, and all of Rep. Walz's family as they go through this unthinkable tragedy," Minnesota DFL Chairman Ken Martin said in a statement.

Cook County Sheriff Pat Eliasen said two emergency calls came within a minute of each other. One man was hit by a falling tree on the shores of Clove Lake, near the Canadian border.

Two injured campers were taken to County Northshore Hospital by helicopter and the Gunflint Ambulance service. Eliasen said the condition of the injured people isn't clear.

In a separate incident 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.

Workers from Timberline Tree Service worked to clear yards along Nokay Lake Road, Hwy 8, near Deerwood, Minn. Vickie Kettlewell for MPR News

According to the National Weather Service, the storm Sunday night ripped a roof off a shed in the Stearns County community of Cold Spring. In Minneapolis, two cars were crushed by a tree that fell near Lake Calhoun. One of four people in the car suffered injuries.

Thousands of Minnesota Power customers lost service when storms blew through. About a thousand customers remained without power Monday morning. Xcel Energy also reported several outages around the metro.

The weather service said a surveyor will be out Monday to evaluate the storm damage and determine the severity of the tornadoes.

Linda Engebretson, meteorologist with the weather service in Duluth, said tornadoes and funnel clouds were reported in the northern part of the state.

Willow River in Pine County had between 30 to 40 tree down, most uprooted.

"That's quite a bit of damage, we've got a fairly broad area with spotty damage," she said. "But where it's happened is very significant damage."

Engebretson said a large tree fell on a home and trapped and injured a resident in Crow Wing County.

Most of the heavy damage was reported in Crow Wing County and the Boundary Waters Canoe Area Wilderness.

The National Weather Service also received tornado and funnel cloud reports in Cass and Itasca counties.

The Twin Cities didn't see as much damage, compared to greater Minnesota, but residents reported golf ball-sized hail around the metro.

The Associated Press contributed to this report.

Correction (June 20, 2016): An earlier version of this story misidentified the lake on which Craig Walz was camping.