Asked to leave, the trespasser, wearing blaze-orange and carrying a semiautomatic assault rifle, opened fire on the hunters and didn't stop until his 20-round clip was empty, leaving five people dead and three wounded, authorities said.
The shooter was eventually captured.
The killings baffled authorities and stunned residents in a state where deer hunting is a rite of autumn — a sport practiced by thousands of people who scour the woods for nine days each November with hopes of bagging a trophy buck.
"This is an incredible tragedy, one in which a great family tradition like a deer hunt has turned into such a great loss," Gov. Jim Doyle said Monday.
Jake Hodgkinson, a deputy at the county jail, identified the suspect as Chai Vang but would give no additional details. Paul Schnell, a police spokesman, told CBS Station WCCO-TV Vang is from St. Paul, Minn. He is a member of the Twin Cities' Hmong community. While authorities do not know why he allegedly opened fire, there have been previous clashes between Southeast Asian and white hunters in the region.
Locals have complained that the Hmong, refugees from Laos, do not understand the concept of private property and hunt wherever they see fit. In Minnesota, a fistfight once broke out after Hmong hunters crossed onto private land, said Ilean Her, director of the St. Paul-based Council on Asian Pacific Minnesotans.
The five killed and three wounded were part of a group of 14 or 15 who made their opening-weekend trip to Robert Crotteau's 400-acre property an annual tradition.
The visit was like any other until around noon Sunday. When two or three hunters spotted a man in their hunting platform in a tree on Crotteau's land, they radioed back to the rest of the party at a cabin nearby, and asked who should be there.
"The answer was nobody should be in the deer stand," Sheriff James Meier said.
One of the men approached the intruder and asked him to leave, as Crotteau and the others in the cabin hopped on their all-terrain vehicles and headed to the scene.
"The suspect got down from the deer stand, walked 40 yards, fiddled with his rifle. He took the scope off his rifle, he turned and he opened fire on the group," Meier said.
One of the men who was shot called for help on his radio, but it was too late. The gunman fired again, hitting the people who had just arrived on ATVs.
The gunman was "chasing after them and killing them," Deputy Tim Zeigle said. "He hunted them down."
It is unclear whether anyone returned fire. The members of the hunting party had only one gun among them.
The scene Meier described was one of carnage, the bodies strewn around 100 feet apart. Rescuers from the cabin piled the living onto their vehicles and headed out of the thick woods.
"They grabbed who they could grab and got out of there because they were still under fire," Meier said.
The shooter took off into the woods and eventually came upon two other hunters who had not heard about the shootings. Vang told them he was lost, and they offered him a ride to a warden's truck, Meier said. He was then arrested; authorities plan to bring charges against him later this week.
Van was carrying an SKS 7.62-mm caliber rifle, a cheap but powerful semiautomatic weapon, authorities said.
Killed were Crotteau, 42; his son Joey, 20; Al Laski, 43; Mark Roidt, 28; and Jessica Willers, 27.
Her said she has heard from some people in St. Paul's Hmong community who said they knew Vang, though not well. About 24,000 Hmong live in St. Paul, the highest concentration of any U.S. city. Many cities in Minnesota and Wisconsin have high Hmong populations.
"They said he loves to hunt," Her said. "He is a hunting zealot."
Meier said Vang might have been on the wrong tree stand because he had become lost and wandered unknowingly onto private property. The county has thousands of acres of public hunting land.
Vang spoke good English and investigators said he was cooperating. The sheriff said he was "extremely calm."
The arrest has left some Hmong citizens in his hometown fearful of a backlash.
Michael Yang, a Hmong activist, said various Hmong groups held an emergency meeting Monday to talk about how to respond. Those at the meeting heard stories from some Hmong hunters about friction with white hunters.
The shooting has already provoked racial tension in an area of Wisconsin where deer hunting is steeped in tradition.
"It's pathetic. They let all these foreigners in here, and they walk all over everybody's property," said Jim Arneberg, owner of the Haugen Inn in nearby Haugen.
Hunter Bill Wagner, 72, of Oshkosh, was about two miles away near Deer Lake with a party of nearly 20 other hunters. After they got word of the shooting, he and others went to round up the rest of the party. He said they heard sirens, planes and helicopters and noticed the surrounding roads blocked off.
"When you're hunting you don't expect somebody to try to shoot you and murder you," he said. "You have no idea who is coming up to you."
It took about three hours to round up the other hunters, who were up to four miles apart, Wagner said. "We're all old, dyed-in-wool hunters," he said. "We wouldn't go home because of this but we will keep it in our minds. We're not forgetting it."