A teenager has been killed and eight others wounded after two pupils armed with handguns opened fire on classmates at a Colorado school.
An 18-year-old boy was pronounced dead at the scene following the shooting at Stem School Highlands Ranch near Denver on Tuesday.
Two surviving victims were in a critical condition in hospital, said Douglas County sheriff Tony Spurlock. The others injured were all stable or had been discharged by Wednesday morning.
None of the victims, all aged over 14, have yet been named.
Mr Spurlock said the shooters opened fire separately in two different classrooms of the school, which has 1,850 pupils from nursery through to age 18.
“Two individuals walked into the Stem school, got deep inside the school, and engaged students in two separate locations,” he said.
Devon Erickson, 18, was named as one of the suspects. The other has been identified as a female juvenile. Both were arrested following a confrontation with police.
Mr Spurlock said sheriff’s officers arrived at the school, about 25 miles south of Denver, and “engaged the suspects” within two minutes of the first reports of a shooting.
“I have to believe that the quick response of the officers that got inside that school helped save lives,” he added.
Police radio tapes recorded officers looking for one suspect with black hair wearing a Nirvana hoodie and another with purple and black hair wearing a black hoodie.
As the gunfire rang out, students ran through halls shouting “School shooter!” Some wondered at first if it was a joke or a drill.
“At the moment no one really knew what was going on so I didn’t know they were bullets,” said seventh-grader Sophia Marks. “I just kind of saw like flashes and we heard bangs.”
Chris Elledge, 15, said his teacher told the class to hide behind weight equipment, where they stayed until police arrived.
“They busted in the room, and they were asking if there was any suspects in the room, if we were OK, and they escorted us out to go out to the front of the building,” the teenager added.
Police declined to comment on a possible motive for the rampage, saying it was too early in the investigation, which is being assisted by the FBI.
Local television station Denver 7, citing multiple sources close to the investigation, reported that the younger suspect was in the process of transitioning from female to male and had been bullied.
The sources depicted the motive for the shooting as “revenge and anger towards others at the school”, according to the channel.
The father of one victim, a 17-year-old boy, said one of the shooters had walked into a classroom and “pulled a pistol out of a guitar case and started to shoot”.
Fernando Montoya said his son was shot three times, but survived. The teenager’s friend was also wounded.
“Thank God he is fine,” Mr Montoya said. “Even though he got shot, he’s OK. He’s going to walk out on his feet, so I’m glad. We’re so lucky.”
Television footage showed police vehicles gathered outside a suburban house, where Mr Erickson is believed to live, about two miles from the school.
Police towed a white car with “F*** SOCIETY” spray painted in blue on one side away from the house.
Medical helicopters landed and took off outside the school as the shooting unfolded.
Young children were seen leaving the building in single file with their hands on their heads, as police officers with rifles stood by a group of high schoolers huddled behind bins, many of them typing on their phones.
Stunned nursery children and weeping high school students were reunited with their parents at a nearby recreation centre.
Stem School, which specialises in science, technology, engineering and maths, spoke of “unspeakable grief and shocking disbelief” in a statement posted on Facebook.
“Our thoughts are with everyone who has been impacted by today’s tragedy, and we are heartened by the bravery of our students, staff, parents and first responders,” it added.
The school will be closed for the rest of the week and pupils and staff will be offered grief support.
The shooting occurred less than a month after the 20th anniversary of the Columbine High School massacre in nearby Littleton, about six miles from the Highlands Ranch school. Two Columbine students killed 13 people in 1999 before taking their own lives suicide in what remains one of the deadliest school shootings in US history.
“Tragically, this community and those surrounding it know all too well these hateful and horrible acts of violence,” said White House spokesman Judd Deere. He added: ”Our prayers are with the victims, family members, and all those affected by today’s shooting.”
Some of the worst mass shootings in the United States have occurred in Colorado. In addition to Columbine, a man opened fire at a cinema in Aurora, another Denver suburb, in 2012, killing 12 people and wounding scores more.
Tuesday’s shooting came a week after a gunman opened fire on the Charlotte campus of the University of North Carolina, killing two people and wounding four. A 22-year-old former student of the university has been charged with murder and attempted murder.
Jason Crow, the Democratic representative for Colorado, called for tougher gun control measures to stem the bloodshed.
“It is not enough to send thoughts and prayers,” he said. ”It is empty. It is weak, and it does an injustice to our children who are on the front lines of this violence.”
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies