A knife-wielding teenager walked into a school in Croatia’s 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 at around 9:50 am (local time) 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.

“The attacker is a 19-year-old who is a former student of that school and still lives nearby,” said interior Minister Davor Bozinovic. “Eventually he started injuring himself. Police prevented him from committing suicide.”

Bozinovic said the attacker had mental health problems and had made a previous attempt to kill himself. “It is hard to say this person was mentally balanced.” School attacks are rare in Croatia and in the Balkans as a whole, although in May 2023, a teenager in Serbia opened fire at a school in Belgrade killing nine 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 on Saturday a day of mourning and cancelled some of the Christmas festivities. Candidates for the upcoming election said they were temporarily suspending their campaigns President Milanovic said “there are no words to describe the grief over the horrible and unthinkable tragedy that shocked us all today”.