In a premeditated assault, a 13-year-old boy gunned killed eight classmates and a security guard in a Belgrade school on Wednesday, forcing Serbia’s president to impose harsher restrictions on gun ownership.

Using two handguns belonging to his father, the boy shot the guard and three girls in a hallway before shooting his teacher and classmates during a history lesson, according to police. The instructor and six students were taken to the hospital, with several suffering life-threatening injuries.

Veselin Milic, head of Belgrade police, said the attacker had two guns and two petrol bombs and had planned everything carefully. “He even had … names of children he wanted to kill and their classes,” he told a press conference.

Gun ownership is widespread in Serbia, which has witnessed several mass shootings over the past decade, and President Aleksandar Vucic said checks would be stepped up.

As Serbia prepared for three days of national mourning, Vucic announced a moratorium on new gun licenses other than for hunting, revision of existing permits and surveillance of shooting ranges and how civilians store their weapons. School shootings are rare.

The shooter, who gave himself up to police and at 13 is below Serbia’s age of criminal responsibility, will be placed in a psychiatric institution, Vucic told reporters, adding that both his father and mother had been arrested.

“He was waiting for this day. He was at the shooting range with his father three times,” Vucic said. The boy had asked for a transfer to another class where he had three friends, he said.

Interior Minister Bratislav Gasic said the suspect’s father, had held the guns legally. Hundreds of thousands of weapons remain unaccounted for in Serbia after the Balkan wars of the 1990s.

“(The boy) … first shot the teacher and then he started shooting randomly,” parent Milan Milosevic told broadcaster N1. Milosevic’s daughter was in the classroom when the attacker burst in, but she escaped.

Thousands of people gathered in the elementary school’s neighbourhood in the evening to lay flowers and light candles.