A teenager was killed and four people were critically wounded after they were stabbed while tubing on a busy Wisconsin river on Saturday, authorities said.
St. Croix County Sheriff Scott Knudson described the scene as "chaotic" and "scary."
"I'm sure that anybody that witnessed it will never forget it," he told reporters during a press briefing Saturday. "It is a tragedy."
Five people were stabbed with a knife while tubing on the Apple River in Somerset Saturday afternoon, the sheriff said.
A 17-year-old boy from Minnesota was transported to an area hospital, where he was pronounced dead, Knudson said.
The four other victims were all believed to have critical injuries, he said. Two victims were transported out of the hard-to-reach area by helicopter and several ambulances responded.
The surviving victims included one woman and three men, all in their early 20s, the sheriff said.
A suspect had fled the scene but was taken into custody without incident, the sheriff's office said.
The sheriff said he was a 52-year-old man from Minnesota. A bystander took a photo of him, which helped authorities in locating him, he said.
Authorities were searching the area for the knife used in the attack and were interviewing a "number of witnesses", Knudson said.
"We're actually in the process of trying to divert some of the tubing traffic around our crime scene," he said. "That alone is causing some challenges trying to get them off the river, and gathering up what we can in a hard-to-get-to area.
It is unclear what led up to the attack, Knudson said.
There is no further threat to the public, the sheriff's office said.
Somerset is located near the Wisconsin-Minnesota border, about 35 miles east of Minneapolis.
The Apple River is a popular destination for tubing and camping.