MADISON, Wis. (AP) — A man who lives in an assisted living complex in a small Wisconsin town opened fire on three fellow residents before apparently shooting himself, the mayor said Thursday.

Life-saving measures were performed at the scene outside Spring Glen Apartments in Mayville after the shooting Wednesday evening. All four people were taken by air to trauma centers, the Wisconsin Department of Justice said. That agency is assisting Mayville police with an investigation.

What led up to the shooting wasn’t clear. Authorities were saying little about the incident. Mayville police referred questions to the DOJ, but the department’s spokeswoman, Gillian Drummond, said she could offer no additional details.

Mayor Rob Boelk said in a telephone interview with The Associated Press that the shooting took place outside the building, which houses about 30 people. The mayor said he didn’t know what precipitated it but that authorities believe the gunman shot himself. He didn’t know the conditions of anyone involved, although the gunman was under armed guard at the hospital where he’s being treated.

A message left at a possible number for the apartment building wasn’t immediately returned Thursday. The building’s Facebook page describes it as a home for the elderly.

Mayville is a city of 5,000 about 50 miles northwest of Milwaukee. There was one homicide in the city from 2015 to 2019, according to statistics compiled by DOJ.

“This is Mayville,” Boelk said. “We don’t ever really have anything like that take place in town.”

Mayville Common Council member Dale Tollner said his ward includes the apartment building. He said no one has told him anything about the shootings. He described the area around the building as “small-town, not rough at all.”

Photos online show Spring Glen Apartments is a long, rectangular, two-story building surrounded by a parking lots on the edge of a wooded area. Across the street stands a McDonald’s, a car wash, storage garages and a family-style restaurant.