(CNN) -- The Tunisian government declared a curfew Tuesday in eight governorates, including the capital city of Tunis, in an attempt to quell violence after protests that included radical Islamists.
The 9 p.m. to 5 a.m. curfew was announced by the Interior Ministry and the Defense Ministry "in the wake of violence carried out by criminal groups against establishments of sovereignty and public and private property," a prime ministry communique said, according to the official Tunis Afrique Press.
The curfew is to be observed in the governorates of Tunis, Ariana, Manouba, Ben Arous, Sousse, Jendouba, Monastir and the Ben Guerdane delegation in the governorate of Medenine, it said.
Medical and night-shift workers are exempted.
The announcement came hours after the offices and archives of the public prosecutor were set ablaze, Tunis Afrique Press said.
The news agency, citing the Interior Ministry, said 97 people had been arrested since Monday night after rioting by "criminal groups" in the capital.
"According to a ministry's press statement, these groups destroyed and set ablaze public properties, attacked police stations and assaulted policemen and citizens," it said. "These groups include Salafis and persons with criminal records."
Salafis are ultraconservatives.
The North African country touched off the Arab Spring by ousting Zine el-Abidine Ben Ali, who was replaced by a moderate Islamist government.
Ben Ali has remained in exile in Saudi Arabia since the January 2011 uprising that forced him from office. He is being tried in absentia in the deaths of dozens of anti-government protesters during the revolt.
Ben Ali already has been convicted in absentia and sentenced to five years in prison for his role in a 1991 case in which 17 servicemen were accused of plotting a coup against his regime.