A schoolboy who killed nine people then himself, walked through a school in the US state of Minnesota shooting as he went, witnesses said.
Many students are reported to have been injured
The gunman, thought to be a local teenager, killed two of his grandparents before going on a rampage at the school, authorities said.
His first victim at Red Lake High School, which is on a Native American reservation, is thought to have been the school's security guard.
Red Lake Fire Director Roman Stately said the teenager then went into a classroom where he shot a teacher and more pupils.
"Apparently, he walked down the hallway shooting and then he entered a classroom, he shot several students and a teacher, then himself," Roman Stately, from the Red Lake Fire Department, told reporters, the AFP news agency reported.
'Boom, boom, boom'
One survivor, Red Lake pupil Sondra Hegstrom, told the Pioneer of Bemidji newspaper that she saw the boy with the gun and looked him in the eye, before running into a classroom to hide.
"You could hear a girl saying, 'No, quit, no Jeff. Quit! Quit! Leave me alone. Why are you doing this?' And then boom, boom, boom, boom, and then no more screaming," she said.
Martha Thunder's 15-year-old son, Cody, was being treated for a gunshot wound to the hip.
Police were alerted to the shootings by phone calls from pupils
"He heard gunshots and the teacher said 'No, that's the janitor's doing something', and the next thing he knew, the kid walked in there and pointed the gun right at him," she said, the Associated Press news agency reported.
Pupil Justin Jourdain told the Minnesota Star Tribune that he thought something had fallen in the hallway when he first heard booming sounds in the school.
A panicked janitor then came in, telling the students to stay in the classroom as "someone's shooting".
The pupils took shelter in an adjacent office, holding the door shut as the gunman entered the classroom, he said.
"I was holding the door and he fired one shot at the door, but it didn't go through. I just heard this loud thud. It was a wooden door and it didn't go through."
Pupils and a teacher, Diane Schwanz, said the gunman tried to break down a door to get into her classroom.
"I just got on the floor and called the cops," Ms Schwanz told the St Paul Pioneer Press. "I was still just half-believing it."
Ashley Morrison, another student who had taken refuge in Ms Schwanz's classroom, called her mother on her mobile phone.
Wendy Morrison said she could hear gunshots on the line. "'Mom, he's trying to get in here and I'm scared'," Ashley Morrison told her mother, the St Paul Pioneer Press reported.
The school's safety director, Pat Mills, told the BBC that pupils were screaming and crying.
"It was chaos at the time. I think the main thing that contributed was that the teachers had a plan, and for whatever reason they fell back on their plan, they got the students out of the school as quickly as possible."
One young pupil told the Pioneer Press he heard seven gunshots, then saw a security guard running toward the high school.
"I heard shooting a bunch of times. Then they said, 'Lockdown! Lockdown!' and I ran to my class. You could hear the shots all the way from the high school to middle school. I was scared."
Police, alerted to the massacre when students used mobile phones to call for help, said they exchanged gunfire with the gunman who ducked into a classroom and shot himself.