Three members of staff at a secondary school in western Bosnia were killed today when an employee opened fire with an automatic rifle before trying to take his own life, police said.
The gunman - who worked as a cleaner - killed the dean, the secretary and an English teacher who had just retired and was helping her replacement at the school in the town of Sanski Most.
No children were killed or injured, and students are currently on their summer holidays. However, some were on the premises for repeat exams, the local police chief Amel Kozlica said.
The gunman, identified by police as Mehmed Vukalic, was severely injured when he sustained a gunshot wound to the chest. Police said that he had used a "military weapon".
He is conscious and awaiting surgery, physicians from the nearby Banja Luka hospital told local television.
The shooting took place at around 10am local time (9am Irish time) about 300km north west of Bosnia's capital Sarajevo.
There are around 40,000 people living in Sanski Most, with many in shock after the deaths.
"We are trying to comprehend why this happened," Mayor Faris Hasanbegovic told a news conference. "There are no words or justification for this".
Some school employees said that Mr Vukalic was unhappy with his job as a cleaner, and that he had suffered from PTSD after the Bosnian war in the 1990s, resulting in absences from work.
Mass shootings are comparatively rare in the western Balkans, despite the fact that the region is awash with weapons that remained in private hands from the wars.
In July, a war veteran in neighbouring Croatia shot five people including his mother in a nursing home and wounded six others.
Additional reporting PA