The woman told officers the man put his arm up to fend off the assault, and the chain saw cut deep into his forearm.
Wichmann said detectives hadn't yet been able to speak with the man, who by the time they were notified of the assault, was heavily sedated at the hospital.
He said there was a language barrier, which made gathering information more difficult, and the woman was very upset by the event. Police hoped to gather more information during follow-up interviews.
Wichmann said police are investigating the condition of the chain saw, but it appears by the man's injuries that the saw was running, but without the chain similar to what is used at haunted houses to give people a scare. Even without a chain, the saw can injure, Wichmann said.
He said police are trying to determine if the assault was intentional or perhaps an attempt at a prank gone horribly wrong.
"Either way we do have a man who was assaulted and a chain saw was used," he said.
Anyone with information is asked to call police at 801-799-3000.