The 16-year-old behind last week's Colorado high school shooting fired off about 20 rounds, mostly inside the school, during an attack that injured two fellow students, authorities said Tuesday.
The attacker fatally shot himself as authorities confronted him outside Evergreen High School, but not before he was able to shoot one of the victims on a nearby street corner, the Jefferson County Sheriff's Office said in a pair of statements.
The attack was reported by multiple callers not long after noon on Wednesday at the campus roughly 30 miles west of Denver, it said.
The gunfire spanned an estimated 9 minutes, the sheriff's office said, with the shooter firing most of the rounds inside the school.
"Shots were fired in several locations inside the school," it said. "One student was injured inside and another injured outside the school."
The sheriff's office credited school employees for putting active shooter training to work quickly.
"While deputies responded quickly, the actions taken by teachers, staff, and students inside the school undoubtedly saved lives," the sheriff's office said. "They relied on the safety protocols and lockdown procedures they have practiced, and those immediate actions made a critical difference."
The shooter was identified as Desmond Holly. The sheriff's office said Tuesday it has confirmed he was the sole attacker that day.
The office said last week the shooter had been "radicalized by an extremist network" but offered no further details.
The Anti-Defamation League's Center on Extremism said over the weekend that the attacker "expressed neo-Nazi views" online and that his TikTok accounts "were filled with white supremacist symbolism."
Two hours before the shooting, the ADL said, he posted a photo of a revolver and ammunition on X, as well as images of a ballistic vest, gas mask and "other gear" on TikTok.
It said he spent "substantial amounts of time" in online spaces focused on extremist ideologies and violence. The FBI said it looked into activity associated with the shooter, who the bureau said spoke online of planning a mass shooting, in July, but at the time could not identify the person and thus could not take action.
One of the two teenagers injured in the attack has been released by hospital staff, sheriff's officials said. The other was in serious condition at the start of the week, it said.
