TUNIS, Tunisia — Tunisian officials moved quickly Wednesday to contain the political fallout after a leading opposition figure was assassinated outside his home, announcing that they would dissolve the Islamist-led government and calling for a unity Cabinet as thousands took to the streets in protests that the security forces beat back with tear gas.
The killing of Chokri Belaid, one of Tunisia’s best-known human rights defenders and a fierce critic of hard-line Islamists known as Salafis, escalated simmering tensions in a society torn between its legacy as a bastion of Arab secularism and its new role as a proving ground for the region’s ascendant Islamist parties.
The explosion of anger, which led to the death of a police officer in Tunis late Wednesday, posed a severe challenge to the ruling moderate Islamist party, Ennahda, which came to power in Tunisia promising to provide a model government that blended Islamist and democratic rule.
Belaid was shot and killed outside his home in an upscale neighborhood of Tunis on Wednesday as he was getting into his car. The interior minister, citing witnesses, said two unidentified gunmen fired on Belaid, striking him with four bullets.
The killing, which was the first political assassination since the overthrow of Tunisia’s autocratic leader, marked a dark turn for the country that set off the Arab uprisings in 2011. It resonated in countries like Egypt and Libya, struggling to contain political violence while looking to Tunisia’s chaotic but orderly transition as a hopeful example.
“Confronting violence, radicalism, and the forces of darkness is the main priorities for societies if they want freedom and democracy,’’ Amr Hamzawy, a member of Egypt’s main secular opposition coalition, wrote on Twitter on Wednesday. ‘‘Assassinating Chokri Belaid is warning bell in Tunisia, and in Egypt, too.’’
The response by Tunisian officials was also being closely watched.Thousands of people took to the streets of Tunis and other cities to protest the assassination. There were clashes on Avenue Habib Bourgiba in Tunis, as riot police fired tear gas and beat protesters.
The prime minister, Hamadi Jabali, called the killing a ‘‘heinous crime against the Tunisian people, against the principle of the revolution and the values of tolerance and acceptance of the other.’’
Bowing to the widespread outrage, Jabali said he was dissolving the Islamist-led government, and replacing Cabinet ministers with technocrats not tied to any political party — an expected move hastened by the crisis. The country’s president, Moncef Marzouki, cut short an overseas trip to deal with the fallout.
Belaid, who was in his late 40s, and others had accused Ennahda of accommodating the Salafis, by refusing to prosecute them or crack down on the groups. In recent days, Belaid, a lawyer who had received numerous death threats including from hard-line imams, had accused Islamists of carrying out an attack on a meeting of his supporters Saturday.
“At the end of our meeting, a group of Ennahda mercenaries and Salafists attacked our activists,’’ Belaid said.
There was no immediate claim of responsibility for the killing. In a statement Wednesday, Ennahda denied any responsibility, saying the killing jeopardized the ‘‘security and stability of Tunisia.’’
In Washington, the State Department spokeswoman, Victoria Nuland, criticized the killing, calling it an ‘‘outrageous and cowardly act.’’
She urged the government in Tunis to conduct a ‘‘fair, transparent, and professional investigation to ensure that the perpetrators are brought to justice consistent with Tunisian law and international norms.’’ Noting the protests that erupted in response to the killing, Nuland called on all Tunisians ‘‘to respect the rule of law, to renounce violence, and to express themselves about this incident and anything else peacefully.’’
As news of the assassination spread, thousands of people gathered in front of the Interior Ministry headquarters, a building that is still a hated symbol of Tunisia’s deposed authoritarian leader, Zine El Abidine Ben Ali, to express anger at Tunisia’s new government.