The teen who perpetrated a massacre at a Serbian school prepared a “kill list” and planned the operation at length

Serbian police said on Wednesday a teenager killed eight fellow students and a security guard at a school in Serbia who had planned the attack for weeks and had a list of people he wanted to kill.

The 13-year-old was arrested following Wednesday’s attack on the Vladislav Ribnekar Primary School in Belgrade. His parents were also arrested.

The crime sparked a major shock in Serbia, where such acts are very rare.

Among the dead, seven of the victims were school girls, but the motive behind the attack remains unclear. Six students and a teacher were wounded in the shooting, four boys and two girls.

A boy was said to have been hit in the neck and chest the most severely, while a girl was said to be in critical condition due to a head injury.

Serbian media says the suspect used two handguns on his father, both of which have legal permits and are registered. It is also said that he went to the shooting range more than once with his father before the murder.

In a televised address to the country, President Aleksandar Vucic described the attack as “the most difficult day in the modern history of our country”. Vucic indicated that the suspect will be sent to a psychiatric clinic.

Under current Serbian law, a teenager cannot be held criminally liable because he is under 14 years of age.

Vucic proposed lowering the age of criminal responsibility to 12 after the crime. He has also proposed several other reforms, including a review of firearms licenses and tighter rules about who has access to shooting ranges.

Police say the suspect planned the attack a month in advance and had a “priority list” of children he would target and which classes he would go to first.

Most of the victims were born in 2009, which means they were 13 or 14 years old at the time of the attack.

Serbia declared a three-day national mourning, which begins on Friday.