Report 35281: Unknown nighttime visitor at a campsite on Lake Jeannette

We were camping  North of Orr MN at Lake Jeanette. Around four in the morning I heard heavy large foot steps coming toward our tent. It was definately on two feet I was wide awake and have no doubt about that. I yelled  Who's there? and it threw a rock at our tent, then walked very fast away. once again with huge heavy foot steps. I tried to recreate the sound of the steps in the morning but was unable to sound that loud. Still wondering what it was.