Jeff Rupnow’s cover photo, posted in August, shows what appears to be a teenaged girl trap shooting with a shotgun at a local club. In a comment on the site, Jeff Rupnow says he and his child joined the club in the spring and “have been loving all every second of it”.

He could not be reached for comment.

In the photo, the girl is wearing a T-shirt with the logo of the German band KMFDM. The teenage shooters in the 1999 Columbine school massacre in Colorado were known to be avid fans of the band, and one of the killers posted the band’s lyrics on his website. A selfie purporting to be of the shooter wearing the T-shirt has also appeared online side by side with one of the Columbine shooter Eric Harris.

At the time, KMFDM issued a statement condemning the attack, expressing sympathy for the victims and affirming its music was intended to stand against violence.

The shooting took place in a study hall classroom just before 11am on Monday, Wisconsin time. Previously, Barnes said the first 911 call reporting the shooting was placed by a second grade student. On Tuesday, he clarified that the call actually came from a second grade teacher.

Two students remained in critical condition, while several other victims suffered less serious injuries, officials said.

Police said Rupnow used a pistol but have not said how it was obtained. Earlier this year, the Michigan parents of a school shooter in that state were found guilty over their role in allowing their son to have access to the gun he used to kill.

Wisconsin officials said it was far too early to say if Rupnow’s parents could be held legally responsible. Barnes said that, for now, it appeared that such charges were not warranted.

School shootings have become a near-daily occurrence in the United States, with 322 of them this year, according to the K-12 School Shooting Database. That is the second-highest total of any year since 1966 – topped only by last year’s total of 349.

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Polling shows American voters favour stronger background checks on gun buyers, temporary limits on people in crisis, and more safety requirements for gun storage at homes with children. Yet political leaders have largely declined to act, citing the US constitutional protection for gun owners.

Dane County executive Melissa Agard said at the press conference that she wanted to see stricter gun laws in Wisconsin – including “Red Flag” laws that could result in guns being confiscated from at-risk people and also laws requiring the safe storage of guns in homes. She called on state and federal legislators to enact better protections.

“Part of that process is setting aside complacency and demanding change,” Agard said. “Let us remember this fact: gun violence is the number one killer of children in this country. That’s a legacy we cannot accept.”