SARAJEVO, Bosnia-Herzegovina (AP) — A school employee shot and killed three people Wednesday in a town in northwestern Bosnia, police said. The shooter was severely injured after trying to kill himself.

The shooting took place around 10 a.m. local time at a secondary school in Sanski Most, about 300 kilometers (180 miles) northwest of Bosnia’s capital, Sarajevo, said regional police spokesman Adnan Beganovic.

Beganovic told The Associated Press that the man used a “military weapon, an automatic rifle." He then attempted to kill himself and is in serious condition in a hospital in nearby Banja Luka.

The victims included the school principal, a secretary and a teacher, said Beganovic. Bosnian schools are closed for the summer holiday, but Beganovic said there were people in the school as repeat examinations were underway.

Regional N1 television reported that the man had a dispute with school management.

No other details were immediately available.

The Balkan region is awash with small arms and weapons since the 1990s wars, part of the breakup of Yugoslavia, particularly in Bosnia, a country of about 3.5 million people. According to a 2010 study by the United Nations Development Program, there were about 750,000 weapons in illegal possession in Bosnia.

Last month, a veteran entered a care home for older people in a quiet central town in Croatia and opened fire, killing six people and wounding six others.

Last May a teenager in Serbia opened fire at a school with his father's guns, killing nine children and a school guard. A day later a 20-year-old shooter killed nine people and wounded 12 in a rampage outside Belgrade, the capital.