Some fled into side-streets or up on to roofs. Others darted under washing lines, into buildings, anywhere to escape the swinging clubs and batons. On the main thoroughfare of a country known more for its package holidays than its propensity for revolt, the air was thick with the soundtrack of insurrection: the crack of gunfire and shattering glass, the sting of teargas, the distant chanting of the determined few carried across on a Mediterranean breeze: "Dictator out!"

And tonight, in a stunning blow to a stubborn regime, the immediate objective appeared to have been achieved, as the news spread through the streets: after 23 years, the president was finally gone, whisked out of Tunis to an unknown destination. Suddenly, the forlorn banners, discarded after a momentous day, were transformed into artefacts of instant history: "Freedom," they declared. "Ben Ali out!"

Earlier, it had not looked so promising. Anti-riot brigades and plainclothes police cornered demonstrators, kicked and beat them with batons, knocked them to the ground and dragged many away to battered vans. Hospital reports spoke of another 12 killed overnight, bringing the toll in a month of violent protest against unemployment and corruption to as many as 70.

The protests, borne of the fury of underemployed youth, the surge in food prices and a well-hidden but visceral revulsion at the ruling family, have provided a rare moment of comeuppance to shock dictators in their opulence everywhere. Zine al-Abidine Ben Ali's vast portraits, which adorned facades up and down the capital, with his black dyed hair and wrinkles carefully airbrushed, were ripped from buildings.

For the first time – in a state where there is estimated to be one police officer for every 40 adults, two thirds of them in plain clothes, and people are afraid of even discussing politics in private for the informers on every corner – people took to the streets today chanting: "Ben Ali out!" and carrying banners saying "Ben Ali murderer!" They railed against his family and that of his loathed wife, Leila Trabelsi, seen as a cross between Imelda Marcos and Catherine de Medici. "Trabelsi thieves!" read one banner, against the woman whose family is reviled for taking tasty slices of state business and contracts, and plundering Tunisia's wealth. Tonight there were reports that some of her family's coastal villas and businesses had been attacked and ransacked.

"Today in Tunis people have said their last word. The people want Ben Ali out, along with his corrupt government which has no credibility," said Mokhtar Aidoudi, a lawyer who was among the protesters. "We want to be able to express ourselves, a free press," said a 20-year-old medical student from Sousse. She railed against the suppression of websites in a nation which lawyers say is the world leader in surveillance and internet censorship, rivalling North Korea and China.

"This is it," said Hussein Bouchabar, a maths teacher who was taken from his classroom in the late 80s and imprisoned for four years for holding views contrary to the regime. Since his release, he has never found work and sells vegetables in a souk. Like others with him at the protest, militia regularly came to his house, to search and ransack it. His phones were tapped, his children could not get university scholarships. "This country is 10 million people living in an open prison, we hope that can change," said a bus driver protesting with him, who showed his ankle swollen from a beating by police.

By early afternoon the jubilant mood was filling protesters with hope as they congregated near the interior ministry, whose basement houses the regime's underground torture chambers. Tunisia is a country with far higher economic growth than its neighbours, at around 5% – even if wealth is concentrated in the hands of its tiny political elite and ruling family. Its high levels of education and women's freedom are unrivalled in the region. "The country is ripe for democracy," said a lawyer, who hoped that if Ben Ali left peacefully and the political landscape reformed then Tunisia could become the first fully functioning, genuinely pluralistic democracy in the Arab world.

"The fear is gone, the people have put away their fear. I've been waiting 20 years for that day," said Sana Ben Achour, of the democratic women's movement.

The spark for the longest-running protest in modern Tunisian history was lit on 17 December in the town of Sidi Bouzid, in the rural interior of Tunisia, a region of olive groves and agriculture which is racked by vast unemployment, repression and poverty a world away from the riches of the Tunisian tourist coast and the propaganda of Tunisia's "economic miracle". Mohamed Bouazizi, 26, an unemployed university graduate, supported his extended family by selling fruit and vegetables from a cart.

When police confiscated his cart, removing his only source of income, he was, his family said, exasperated at the injustice and set himself on fire outside the local governor's office.

His desperate act sparked a wave of copycat suicides and street protests over unemployment but also what one graduate called "the ritual humiliation of the people" and "a corrupt regime". Demonstrations soon spread to the coast and the outskirts of Tunis. They were violently repressed by police.

In rural Kesserine near Sidi Bouzid, police snipers fired from rooftops into the crowd and scenes of chaos in the local hospital sparked comparisons with Iraq.

Khadija Sharif, a sociologist and university lecturer in Tunis, said: "For years, Ben Ali set about killing off political opposition parties, weakening and dividing them. The street protests are spontaneous, not a movement with a leader.

"Nor has Ben Ali prepared any succession of his own. It's the complete unknown. We're afraid of chaos, no one knows whether there is a possibility of a military coup, or of an Islamist presence."

A senior figure from the Tajdid opposition party said: "There has to be profound democratic change but that will be extremely difficult.

"If it works, it could be the first true democracy in the Arab world. But we must be vigilant and avoid all naivety. Totalitarianism and despotism aren't dead. The state is still polluted by that political system, the ancien regime and its symbols which have been in place for 55 years."