Jaylen Fryberg was well liked and athletic, a football player named to his high school's homecoming court just one week ago.
He was also facing problems, writing of some unspecified troubles on his Twitter feed: "It breaks me... It actually does...."
The popular Marysville-Pilchuck High School freshman opened fire in the school's cafeteria late Friday morning, a government official with direct knowledge of the shooting told The Associated Press.
One girl was killed and four other young people — including two of the gunman's cousins — were badly wounded before Fryberg fatally shot himself, witnesses, police and relatives said.
His motives remained unclear. Some students described Fryberg as happy and social, even though he had recently fought with a boy over a girl.
Shaylee Bass, a 15-year-old sophomore, said he remained upset about that, but she was stunned by the shooting.
"He was not a violent person," she said. "His family is known all around town. He was very well known. That's what makes it so bizarre."
Students said the gunman stared at his victims as he fired. The shootings set off a chaotic scene as students ran from the cafeteria and building in a frantic dash to safety, while others huddled inside classrooms at the school 30 miles north of Seattle.
Marysville police declined to release the shooter's identity, with Chief Rick Smith insisting he did not want to "dramatize someone who perpetuated a violent crime in a place where children should feel safe."
But many students identified Fryberg as the gunman, and the identity was confirmed to The Associated Press by a government official who spoke on condition of anonymity because he was not authorized to speak to the media.
Students and parents said Fryberg was a member of a prominent family from the nearby Tulalip Indian tribes and was a freshman football player. A week ago, he stood on the high school track during the team's homecoming game in a vest, tie and white sash as he was introduced as a prince, according to a video recorded by parent Jim McGauhey.
Marysville Police Commander Robb Lamoureux said the gunman died of a self-inflicted wound, but he could not provide more details.
Three of the victims had head wounds and were in critical condition. Two unidentified young women were at Providence Everett Medical Center, and 15-year-old Andrew Fryberg was at Harborview Medical Center in Seattle, a hospital official said.
Another victim, 14-year-old Nate Hatch, was listed in serious condition at Harborview, the hospital said. Family members told KIRO-TV that Andrew Fryberg and Hatch are cousins of Jaylen Fryberg.
Witnesses described the shooter as methodical inside the cafeteria.
Isabella MacKeige, 18, was having lunch with a friend when the suddenly heard gunshots behind them.
"I heard six shots go off and I turned and saw people diving under the tables," she told The Associated Press. "In my brain I thought 'run!' So I left my backpack, my phone and my purse and got out the door as fast as I could."
Some students got hurt when they tripped and fell in the chaos, she said. They ran across an open field to the fence that circles the schoolyard and climbed over.
She kept running until she felt safe and found a phone.
"I called my mom and she said, 'stay where you are - I don't want to lose you,'" MacKeige said.
Fryberg's Twitter feed suggested he was struggling with an unidentified problem.
On Wednesday, a posting read: "It won't last ... It'll never last." On Monday, another said: "I should have listened. ... You were right ... The whole time you were right."