A 22-year-old man apparently shot and killed three people and wounded a fourth at a home on a South Dakota American Indian reservation early on Saturday, before he killed himself, authorities said.

The state attorney general’s office said in a news release that the attack happened at a home in Sisseton, a town on the Lake Traverse Reservation, which is in the north-east corner of the state near the borders with North Dakota and Minnesota.

The attorney general’s office identified the alleged attacker as a local man, Colter Richard Arbach. It did not identify the victims or say how they knew Arbach. Nor did it release any other information on the shooting.

A Sisseton hospital official said a woman wounded in the attack was flown to Fargo hospital and was in stable condition.

Joyce Arbach, of Sisseton, said she was related to Colter Arbach but that her family and his did not associate much. She said she had not seen him since she was a substitute aide and teacher at Sisseton high school, from which he graduated in 2011. Her son was his classmate.

“He was a good kid. He was quiet and polite, well mannered. But that was then,” Joyce Arbach said. “This is really kind of a shock because I never would have expected anything like this from him.”

Nearly half of Sisseton’s 2,470 residents in 2010 were Native American, according to the census.