DES MOINES, Iowa (AP) — The teenage shooter in a deadly attack at a small-town Iowa high school in January sought to gain fame with the shooting, tried to livestream his actions and had planned for weeks, according to investigators.

The town of Perry, located about 30 miles (48 kilometers) northwest of Des Moines, was rocked when 17-year-old Perry High School student Dylan Butler opened fire on students and staff before the start of classes on Jan. 4, the first day back after the winter break. Butler took his own life with a single gunshot minutes after shooting at others.

The shooting occurred in the school's commons area, where about 50 students and staff had gathered for breakfast before classes. According to a new report summarizing the investigation, Butler arrived at the school at 7:12 a.m. with a shotgun, revolver, knife and homemade explosive device concealed on him and immediately went to a bathroom near the commons area. While in the restroom, Butler posted on social media and began livestreaming, the report said.

The livestream was active on Instagram for a “very, very short period of time” before parent company Meta took it down, Iowa Department of Public Safety Commissioner Stephan Bayens said Friday during a news conference. Butler had a limited following on the platform, so it is unlikely many people saw the livestream, which Meta later provided to investigators, Bayens said.

Evidence gathered suggested Butler showed signs of an obsession with violence and school shootings at least a year prior and had begun planning the shooting six or more weeks beforehand, Bayens added.

Bayens noted there was no evidence to substantiate claims that Butler was acting on a grievance or because he was bullied, as some who knew him had suggested.

Based on Butler's writings, “he desired to be famous, he desired to commit suicide, he desired to take others with him," Bayens said.

The Iowa Division of Criminal Investigation conducted an exhaustive investigation, Bayens said Friday. Based on that investigation, Dallas County Attorney Jeannine Ritchie released a report Thursday summarizing the findings and her office's assessment of criminality. They concluded Butler acted alone and the investigation found no evidence that anyone had specific knowledge of Butler’s plans or helped him in the shooting.

Butler emerged from the bathroom 23 minutes after arriving at the school, wielding the shotgun, and began firing. Within the first 24 seconds, Butler fatally shot 11-year-old sixth-grader Ahmir Jolliff and wounded four other students and Perry High School Principal Dan Marburger, the report said.

Bayens and Ritchie both highlighted the heroic actions of Marburger and others to intervene, detailing how the principal and Assistant Principal Brad Snowgren moved towards the source of the gunfire when it began.

Snowgren triggered an alarm informing first responders of an active shooting at the school 10 seconds after the first shot was fired and 25 seconds before the first 911 call, the report said. The first police officer entered the school less than two minutes after that alert, much sooner than the “less than seven minutes” initially reported.

The report says Marburger had a chance to escape the building but remained inside and pleaded with Butler to stop shooting. Bayens said Marburger “saved lives that day” by distracting Butler, calling out his name repeatedly to allow others time to escape.

Investigators could not determine how or where Butler retrieved the shotgun he used, but Bayens said it was probably resold in a private sale and “likely came from a large gun collection within the extended family … and was likely taken without the owner’s knowledge.”

The handgun Butler carried into the school was not used in the shooting and had been taken from an unsecured place in his parents' home, investigators determined. Regardless, Ritchie wrote that Butler's parents were unaware of his plans and evidence in the case “does not support charges at the state level against anyone.”

School staff frequently interacted with Butler, according to the report, but they had no reports regarding Butler’s intentions on the day of the shooting. Butler also was not the subject of any prior law enforcement investigations or threat assessments, the report said.

However, investigators found Butler had shared an obsession with prior school shootings with people in the community and online chat rooms, and he had years of behavioral and mental health concerns that were known by people in his life.

“I can say that others were aware of the shooter's general interest in school shootings. Others were aware of his fascination for violence. Others were aware of his concerning behaviors,” he said. “Those concerns, along with a number of other warning signs, were unreported or were otherwise unrecognized.”

Bayens said some people interviewed indicated their regret for not reporting concerns and implored people to speak up.

“School safety strategy has to be holistic,” he said. “We need parents, we need teachers, we need friends. We need those partnerships if we're going to prevent this.”