Police have released a mugshot of the teenager suspected of killing at least 17 people in a Valentine's Day school shooting in Florida.
Nikolas Cruz,a 19-year-old former student who was expelled from Marjory Stoneman Douglas High School in Parkland, has been arrested over the shooting on suspicion of perpetrating the massacre. He was equipped with at least one rifle, police said.
In an evening press conference, Sheriff Scott Israel said 12 victims had been identified from the school, including an American football coach.
Details about the suspect are slowly emerging, with peers describing him as a loner who had previously threatened other students.
Kim Kardashian West and actress Julianne Moore were among those calling for stronger restrictions in the wake of the atrocity.
Boogie Nights actress Moore tweeted: "The 18th school shooting in the US since January. It is heartbreaking. What will it take to change our nation's gun laws ???"
Kardashian West said: "We owe it to our children and our teachers to keep them safe while at school. Prayers won't do this: action will. Congress, please do your job and protect Americans from senseless gun violence."
Singer Nancy Sinatra called on the Republican Party to pass "sensible" gun laws immediately.
"Seventeen more of our young people dead, killed by a shooter with an automatic weapon he had no business having," she added.
Talk show host Ellen DeGeneres said: "No words, no actions, no laws are enough until we end this epidemic of school shootings in our country."
Actress Reese Witherspoon said she was "heartbroken" by the attack, adding "enough is enough".
In the late press conference, Florida Governor Rick Scott, a Republican, said it was an act of "pure evil" but refused to discuss gun controls. Israel earlier said that the suspect had at least one AR-15 rifle and multiple magazines.
The school had been placed on lockdown before the suspect was apprehended.
US President Donald Trump sent his "prayers and condolences" to the families of those who died in the "terrible" shooting.