According to investigators, the kid who killed eight other students and a security officer in a Serbian school had been planning the attack for weeks and had a “kill list.”
Following the attack at the Vladislav Ribnikar primary school in central Belgrade on Wednesday morning, the 13-year-old was detained.
Another six pupils and a teacher were also injured in the shooting.
The motive for the attack is still being investigated, police said.
Officers in helmets and bulletproof vests cordoned off the area around the school, located in the central Vracar neighbourhood, shortly after 08:40 (06:40 GMT)
Police have identified the suspect as Kosta Kecmanovic, and he is suspected of using two legal firearms belonging to his father. Additionally, it is claimed that before the killings, he frequently visited a shooting range with his father.
Since then, the boy’s parents have both been placed under custody.
President Aleksandar Vucic referred to the incident as “the most difficult day in the modern history of our country” in a televised speech to the nation.
He declared that the suspect will be taken to a mental health facility. He cannot be charged with a crime in Serbia currently because he is under the age of 14.
Mr Vucic has suggested that the age of criminal liability may be lowered to 12 in the wake of the killings.
He has also proposed several other reforms, including an audit on firearms licences and a tightening of the rules around who can access shooting ranges.
Police say the suspect planned the attack a month in advance and that he had carried a “priority list” of children to target and which classrooms he would go into first
Since the majority of the victims were born in 2009, they were either 13 or 14 years old when the incident occurred.
There will be a three-day national mourning period beginning on Friday.
Four more boys and two more girls, along with seven girls and one boy who have been confirmed dead, were injured.
The worst injuries were reportedly sustained by a child who was shot in the neck and chest, while a girl with a head injury is in severe condition.
Three other boys suffered injuries to their legs, while a second girl was shot in the abdomen and is currently stable.
“There’s been an operation and all that can be done [has been] but they’re still fighting for her life”, the health minister said
The minister claimed that the life of a teacher who was hurt in the incident and was reportedly having surgery.
Hours after the incident, parents’ sobs could be heard on the school’s neighbourhood streets.
One of the students’ fathers, Milan Milosevic, said that his daughter was in the class where the gun was fired and that she was able to flee.
“[The boy] shot the teacher first, and then he started shooting randomly,” Mr. Milosevic said to broadcaster N1.