Judge Julian Goose said Rudakubana should serve a minimum of 52 years. He said he could not impose a full life sentence as Rudakubana was 17 when the attack took place but he was unlikely ever to be released.

Twice during Thursday’s hearing, Rudakubana was removed from the dock after shouting he was unwell. He refused to return to court to hear his sentence.

The court was shown harrowing video footage of screaming girls fleeing the building. One bloodied girl collapsed outside, provoking gasps and sobs from the court’s public gallery.

“He targeted us because we were women and girls, vulnerable and easy prey,” Leanne Lucas, 36, the yoga teacher who organised the event and was stabbed five times, told the court.

Bebe King, six, Elsie Dot Stancombe, seven, and Alice Dasilva Aguiar, nine, were killed. They were among 26 children attending the summer vacation event.

Two suffered at least 85 and 122 sharp force injuries Heer said, saying it appeared he had tried to decapitate one of them.

After his arrest, Rudakubana told police: “I’m glad those kids are dead, it makes me happy.”

Images and documents found on a computer at his home showed a long obsession with violence, killing and genocide, Heer said.

Rudakubana also admitted possessing an al Qaeda training manual and producing ricin, a deadly poison which the judge said it was likely the teenager would have used.

Heer said the murders were not considered terrorism as Rudakubana was not inspired by any particular political or religious ideology. Material mocking religions including Islam, Judaism and Christianity had been found on his devices.

“It is not possible to identify any particular terrorist cause,” Heer said. “Rather, the evidence suggests that the defendant’s purpose was the commission of mass murder as an end in itself.”

Rudakubana had been diagnosed with autism but his lawyer, Stan Reiz, said he did not have a mental disorder that explained his actions and there was little he could offer in mitigation for “such wickedness”.

Heer said Rudakubana had in 2019 contacted a helpline for children and asked: “What should I do if I want to kill somebody?”

Soon afterwards, he was expelled from school after admitting bringing in a knife 10 times, and was arrested with a knife in his backpack after returning and attacking a pupil with a hockey stick, Heer said.

Rudakubana had been referred to a counter-radicalisation scheme, Prevent, after researching school shootings, uploading images of late Libyan leader Muammar Gaddafi to Instagram and researching an attack in London, but no action was taken.

The government has ordered a public inquiry, saying there were grave questions to answer.

“After one of the most harrowing moments in our country’s history we owe it to these innocent young girls and all those affected to deliver the change that they deserve,” Starmer said.-Agencies