INTERNATIONAL FALLS, Minn. (AP) — A park ranger died while trying to save three people during a water rescue at a national park in Minnesota.

The National Park Service said the ranger responded Sunday to a call for assistance on Namakan Lake in Voyageurs National Park near the Canadian border. Officials said their boat had become disabled during high winds and rough waters.

The ranger arrived and was towing the distressed boat to safety when the National Park Service boat capsized, sending all four people into the water.

The three people being rescued were able to swim to safety. The ranger’s body was recovered about three hours later. The name of the ranger has not been released.

The park service said an investigation is ongoing.