ZAGREB, Croatia (AP) — Hundreds walked in silence in Croatia's capital on Monday, seeking action after a pupil was killed and three other children were wounded in a knife attack at a school in Zagreb.

Organized by teachers' unions, the march asked authorities do more to ensure that schools in Croatia are safe for children. Similar events were held in other cities and towns.

"We need support from government institutions, school teams, media, civil society organizations and all the people who are involved," about 50 teachers' groups and other organizations said in a joint statement.

Croatia's ministry of education said it has held meetings of expert teams tasked with finding ways of improving school security. Minister Radovan Fuchs said measures could include locking school doors or entry control.

Officials said the suspected attacker was a 19-year-old former student of the primary school in Precko and still lives in the neighborhood. The young man was cutting himself when police apprehended him.

School attacks are rare in Croatia and in the Balkans as a whole. In May 2023, a teenager in neighboring Serbia opened fire at a school in the capital, Belgrade, killing nine fellow students and a school guard.