Passengers in buses by the city's public transportation enterprise were attacked on Wednesday and Thursday by unknown perpetrators. Police launch investigation to find them, while those injured have received medical attention, according to the Interior Ministry (MoI).

On Wednesday evening, a group of teenagers got onto a bus and assaulted five people without saying anything to them.

The second incident took place around midnight when a group of people tried to forcibly enter a bus. Some of them started throwing stones and items at the bus, thus injuring two passengers. The driver also was also attacked.

Criminal charges are expected to be filed against the perpetrators in both incidents.

Interior Minister Gordana Jankuloska on Thursday strongly condemned the incidents and appealed to the citizens to act "seriously."

"Violence can have a tragic ending and there is no justification for that. It is irrelevant from which ethnic community these perpetrators originate," she stressed.

MoI has already heightened the level of security in Skopje and preventive measures are being taken.

Jankuloska told a press conference that the incidents were most likely not coordinated, having different motives.

"All of us need to make efforts to calm the tensions down," the minister said adding that many people in Macedonia didn't wish inter-ethnic relations to be disrupted.