Police spent almost two hours trying to catch a suspect who shed his clothes and dashed in and out of a city lake to evade capture.
The cat-and-mouse pursuit began when the 32-year-old suspect allegedly tackled two teenagers to the ground at Green Lake Park in Seattle, in the US state of Washington, on Tuesday afternoon.
Police say they do not know what provoked the attack.
The witness said good Samaritans chased the bearded man around the lake, but "he could sprint like you wouldn't believe."
When police arrived on the scene, the suspect threw his sleeping bag at them and jumped into the lake, according to reports.
He then swam into the centre of the lake, held onto a buoy and refused to surrender.
Police in two small boats and divers soon arrived, along with a crisis intervention officer, but the suspect continued to elude them.
At one point, he pushed a police boat away and even swam under his pursuers' boats to evade arrest.
Eventually the man agreed to climb aboard a boat and be taken back to shore.
He was wrapped in a blanket and an ambulance took him to a nearby hospital for evaluation.
A 19-year-old man suffered a broken finger and a busted lip in the tackle assault, while his 16-year-old sister sustained a few scrapes.