BELGRADE: Serbian education minister Branko Ruzic resigned on Sunday, four days after a school shooting that saw a 13-year-old kill eight students and a security guard.

Ruzic offered his condolences to the victims' families of a "cataclysmic tragedy" that has rocked the Balkan nation in an open letter sent to Serbian Prime Minister Ana Brnabic.

"As a responsible and well-mannered person, professional in performing all previous public duties... I submit my irrevocable resignation from the position of Minister of Education in the Government of the Republic of Serbia," Ruzic said in a letter he shared on Twitter.

Serbian president vows to ‘disarm’ country after mass shootings

The 47-year-old prominent member of Socialist Party of Serbia -- a junior coalition partner in government -- originally blamed the internet, video games and "western values" for the unprecedented massacre.

Opposition parties and human rights groups immediately called for minister's resignation, while thousands gathered in front of the ministry a day after the shooting conveying the same message.

Less than 48 hours after the school shooting, the small Balkan country was shocked again with another massacre as a 21-year-old gunned down eight people in a village near the capital Belgrade.

Serbian President Aleksandar Vucic pledged to launch a large-scale disarmament plan, while police vowed to deploy officers to patrol around schools.

Serbia has among the highest gun ownership rates in the world, with more than 39 firearms for every 100 civilians, according to the Small Arms Survey project.