(CNN) -- Police in the northern city of El Kef opened fire on a crowd of protesters in Tunisia on Saturday after demonstrators reportedly became violent, the country's official news agency reported.

About a thousand people were outside the police station when authorities fired shots, killing two people and injuring 17, Tunis Afrique Presse, or TAP, said. It was not immediately clear why the protesters were there.

The news agency reported that demonstrators threw stones and Molotov cocktails at the building and burned two cars. Police fired tear gas and then shots in the air. When protesters did not respond, they fired into the crowd, TAP said.

Tunisia remains on edge ever since longtime strongman Zine El Abidine Ben Ali fled the country on January 14, following weeks of protests against poor living conditions, high unemployment, government corruption and repression that left 100 dead.