According to police, a seven-year-old girl was killed and six other people were injured in a knife attack at a school in Croatia

A 7-year-old girl was killed and at least five other students and a teacher were injured in a knife attack at a school in the Croatian capital Zagreb on Friday, police said. The local hospital said the wounded teacher suffered life-threatening injuries, Reuters reported.

Officials said the attack occurred at 9:50 a.m. local time at Precko Elementary School in the neighborhood of the same name. They described the attacker as a “young man” and said he had been arrested.

The Croatian Interior Ministry said the attacker was 19 years old. Local media reported that the attacker was a former student of the school and showed video footage of children running away from the school building and a medical helicopter landing in the school yard.

Croatian Prime Minister Andrej Plenkovic said he was “horrified” by the attack and authorities were still working to determine the exact incident. He said several children were taken to different hospitals in Zagreb.

State television reported that the attacker went straight to the first classroom he found after entering the school and attacked the students and their teacher there.

Attacks on schools are rare in Croatia. Last May, a teenager in neighboring Serbia opened fire on a school in the capital Belgrade. nine classmates and a school guard were killed.