A knife-wielding teenager walked into a school in Croatia鈥檚 capital on Friday, stabbed a 7-year-old girl to death and wounded three more children and their teacher, authorities said.

The attack took place around 9:50 a.m. on the last day of school before Christmas at the Precko Elementary School in the Zagreb neighborhood of the same name. It caters for children between the ages of 7 and 15.

鈥淭he attacker is a 19-year-old who is a former student of that school and still lives nearby,鈥� said Interior Minister Davor Bozinovic. 鈥淓ventually he started injuring himself. Police prevented him from committing suicide.鈥�

Bozinovic said the attacker had mental health problems and had made a previous attempt to kill himself. 鈥淚t is hard to say this person was mentally balanced.鈥�

School attacks are rare in Croatia and in the Balkans as a whole, although in May 2023, in the capital, Belgrade, killing nine fellow students and a school guard.

Video footage broadcast by Croatian media on Friday showed children running away from the school building and a medical helicopter landing in the schoolyard.

Authorities in Croatia declared Saturday a day or mourning and canceled some of the Christmas festivities. Candidates for the upcoming presidential election said they were temporarily suspending their campaigns because of the tragedy.

President Zoran Milanovic said 鈥渢here are no words to describe the grief over the horrible and unthinkable tragedy that shocked us all today.鈥� Milanovic called for unity and an effort to ensure that schools are a safe and carefree place for children.

Prime Minister Andrej Plenkovic said at a government session that he was 鈥渁ppalled鈥� by the attack and that authorities are still working to determine exactly what happened.