Tunisia has dissolved its government in an attempt to stem violent protests sparked by the assassination of a liberal opposition politician, in the biggest threat to the country's stability since the Arab Spring.
The Prime Minister Hamadi Jebali took the decision to install a unity administration of technocrats until elections can be held after Chokri Belaid was shot dead outside his home in the capital, Tunis. Mr Belaid was an outspoken critic of the coalition government led by Mr Jebali's moderate Islamist Ennahda Party, which family members were quick to blame for the killing.
Since its uprising successfully toppled Zine el-Abidine Ben Ali in January 2011, Tunisia has traversed a relatively peaceful road to democracy but has become increasingly politically polarised in recent months, with secularists pitted against Islamists. The assassination marked a dangerous turning point as Avenue Habib Bourguiba – a tree-lined thoroughfare in central Tunis that was the focus of protests during the revolution – was once again choked with tear gas.
"This is a sad day that shook the country," Mr Jebali said in an address to the nation, admitting weeks of political deadlock to form a new more inclusive cabinet had failed. "We are at a crossroads and we will learn from it to make a peaceful Tunisia, secure and pluralist, where we may differ but not kill each other."
Earlier in the day police used tear gas to disperse incensed crowds in a number of cities, who gathered calling for a "second revolution".
Thousands of protesters gathered outside the interior ministry, swarming around an ambulance carrying the dead politician's body, chanting, "The people want the fall of the regime" – a familiar slogan during the uprising.
As the day wore on the demonstrations turned violent, with some protesters throwing rocks and bottles before being dispersed. Mr Belaid, the leader of the Unified Democratic Nationalist Party, was hit by four bullets to the head and chest as he left home for his office, according to a politician in his leftist alliance.
An interior ministry spokesman Khaled Tarrouch said he was shot at point-blank range by a man who fled on a motorcycle with an accomplice.
"This is a letter being sent to us that we will refuse to open," President Moncef Marzouki said of the assassination as he cut short a visit to France. Mr Belaid, 48, a trained lawyer, had been a vehement opponent of Ben Ali and his opulent lifestyle, but since the authoritarian ruler was toppled had turned his criticism to the country's new Islamist-dominated government. The French President François Hollande described him as one of Tunisia's "most courageous and free voices".
Mr Belaid's outspoken secular views had earned him enemies and he had received numerous death threats, according to his family. After an attack on a meeting of his supporters at the weekend he claimed that "mercenaries" acting on behalf of the Ennahda Party were responsible.
"All those who oppose Ennahda become the targets of violence," he said the night before he was killed.
His wife Basma said she would file murder charges against the Ennahda Party and its leader Rached Ghannouchi, whom she described as "personally" responsible.
"I saw his blood flowing, I saw his little smile. I saw that they want to kill democracy," she said in an interview with France's Europe 1 radio.
Mr Ghannouchi vehemently denied any involvement by his party in the killing. He accused the assassins of attempting to create a "bloodbath" in Tunisia, but his words did little to quell the anger on the streets and politicians took to Tunisia's television stations to trade insults, stirring tensions further.
The Ennahda office in the central Tunisian city of Mezzouna was ransacked, while protesters torched others in the mining community of Gafsa and also el-Kef.
The Tunisian street vendor Mohamed Bouazizi – who is credited with sparking the Arab Spring protests – set himself on fire in a suicide protest against Ben Ali's government in January 2011. But the economic hardships that drove Bouazizi to his death still persist, raising pressure on the country's leadership.
Tunisia is still racked by unemployment, particularly in the interior, and the government has been accused of curtailing press freedoms. Nearly 90 per cent of the country's journalists went on strike in October after the Ennahda Party installed loyalists at the head of state media organisations in direct contravention of press laws drafted in the wake of the uprising.
Shadi Hamid, an analyst at the Brookings Doha Centre who was in Tunis to meet officials, said the atmosphere was one of "shock and tension".
"People are afraid this is a sign of things to come," he said. "It could be the start of low-level instability and violence on a regular basis. That's the direction Egypt has gone in. Tunisia was supposed to be the exception to the rule but it looks like that might not be the case."