Crandon, Wis. ? An off-duty sheriff’s deputy went on a shooting rampage early Sunday at a home where seven young people had gathered for pizza and movies, killing six and critically injuring the other before authorities fatally shot him, officials said.

The gunman, Tyler Peterson, was 20 years old and worked full-time as a Forest County deputy sheriff and part-time as a Crandon police officer, said Police Chief John Dennee.

Three of the victims were students at the small town’s high school, and three were recent graduates, a school official said. The gunman may have graduated from the same high school.

Peterson was not working at the time of the shooting, Sheriff Keith Van Cleve said.

The survivor was in critical condition Sunday night at a hospital in nearby Marshfield, according to a nursing supervisor. A Crandon police officer who fired back was treated for minor injuries and released.

Gary Bradley, mayor of the city of about 2,000, said earlier Sunday that a sniper killed the suspect, but Van Cleve would not confirm that officers shot the suspect.

Peterson was killed Sunday afternoon eight miles north of Crandon in the rural town of Argonne, Dennee said.

The circumstances of the shooting were hazy Sunday and it wasn’t immediately clear what the gunman’s motive was, but the mother of a 14-year-old victim said the suspect may have been a jealous boyfriend. The shooting occurred in a white, two-story duplex about a block from downtown Crandon.

“It was a pizza and movie party,” Dennee said.

Three of the victims were Crandon High School students, said schools Superintendent Richard Peters, and the other three had graduated within the past three years.

“There is probably nobody in Crandon who is not affected by this,” Peters said, adding that students would be especially affected. “They are going to wake up in shock and disbelief and a lot of pain.”

The sheriff said he would meet with state Attorney General J.B. Van Hollen this morning to discuss the case. Dennee said the state Department of Criminal Investigation will handle the case because the suspect was a deputy and officer.

The Crandon School District called off today’s classes.

The community, about 225 miles north of Milwaukee in an area known for logging and outdoor activities, is facing a trying time but is pulling together, Bradley said.

“We are a strong community. We always have been,” he said. “This is agonizing, but we will prevail.”