Police fired at an angry crowd of 1,000 attacking the police station in the northwestern town of Klef on Saturday, killing two people and injuring 17 others, the Interior Ministry said.
The official Tunisian news agency said the crowd had turned on police after the police chief "abused" a member of the community. A local journalist said the police chief slapped a woman during a demonstration, triggering the violence between police and citizens.
The journalist said that two other people died on the way to the hospital, but that information could not be officially confirmed. The journalist, reached by telephone, asked not to be identified for professional reasons.
Regional prefect Mohamed Najib Tlijali, calling for calm on a local radio station, said that the police official was himself hospitalized but under arrest.
The clash pitting police against citizens appeared to be among the most serious since this small North African country began a process of moving out of a 23-year-long dictatorship with the flight into exile of President Zine El Abidine Ben Ali on Jan. 14 following a month of demonstrations.
A statement by the Interior Ministry, which is in charge of police, said that some 1,000 citizens threw stones and small firebombs at the police station in a surge of anger after the "abuse" by the police chief. The crowd burned two cars, one a police vehicle, a ministry statement said.
Police fired tear gas, then fired into the air in a vain effort to disperse the crowd, then began firing on demonstrators, the Interior Ministry said.
The statement did not specify the nature of the abuse by the police chief that triggered the incident, but the eyewitness said a woman was slapped. The ministry confirmed the police chief was under arrest and said investigators had been sent to Kef.
Tunisia remains tense since demonstrations pushed Ben Ali into exile in Saudi Arabia. Police, in particular, were long distrusted by the population because they carried out the repressive policies of Ben Ali's regime.
The demonstrations that set of Tunisia's "people's revolution" began in the nation's heartland when an unemployed man in the central western town of Sidi Bouzid set himself afire Dec. 17 after police confiscated his fruit and vegetable cart because he had no legal authorization to sell. A woman police officer reportedly slapped the man in a major affront to his dignity.
The Tunisian uprising has since spread to Egypt where tens of thousands have demonstrated for nearly two weeks calling for the ouster of President Hosni Mubarak.