Two weeks ago a peaceful demonstration turned into an ongoing series of protests and riots. Residents were defiant of Prime Minister Recep Tayyip Erdogan's orders to disperse.
The unrest has spread to 78 cities across the country, with protesters championing their objections to what they say is the prime minister's increasingly authoritarian style and his perceived attempts to impose a religious and conservative lifestyle in a country with secular laws - charges he rejects.
Riot police met protesters Tuesday in Taksim Square with tear gas, rubber bullets and water cannons. Protesters have been occupying the area for the past 12 days.
Hundreds vowed to continue their sit-in at Taksim's adjacent Gezi Park, despite an order from Erdogan for them to leave - an order bolstered by the police show of force.
Four people have died, including a policeman, and about 5,000 people have been injured, according to the Turkish Human Rights Foundation.
Tuesday's clashes, which saw police and protesters take and lose control of the square several times, came a day after Taksim saw its smallest gathering since the demonstrations began, sparked by a violent police reaction against a sit-in in the park to prevent its redevelopment. The government had also said Erdogan would meet with some of those occupying the park on Wednesday to hear their views.
Erdogan, a devout Muslim, says he is committed to Turkey's secular laws and denies charges of autocracy. Yet as he defended his tough stance, he gave critics little hope of a shift in his position.
Confident of his position of power after winning the last elections in 2011 with 50 percent of the vote, Erdogan has insisted he will prevail. He made it clear that he has come to the end of his patience with the protesters, whom he accused of sullying Turkey's image abroad and being vandals and troublemakers.
"To those who ... are at Taksim and elsewhere taking part in the demonstrations with sincere feelings: I call on you to leave those places and to end these incidents and I send you my love. But for those who want to continue with the incidents I say: 'It's over.' As of now we have no tolerance for them."
"Not only will we end the actions, we will be at the necks of the provocateurs and terrorists, and no one will get away with it," he added.
Istanbul Governor Huseyin Avni Mutlu asked peaceful protesters to stay away from Taksim until it was cleared of "marginal groups." He said some 30,000-35,000 had gathered as police stood by. Police fired tear gas to disperse them because some attacked police.
Ambulances ferried away the injured. Before the evening clashes, more than 300 people had already been treated in a makeshift infirmary set up in the park, most for the effects of tear gas, said volunteer Selin Akuner. Twelve had suffered head injuries.
In the square, water cannons doused a man in a wheelchair carrying a Turkish flag as a phalanx of helmeted officers moved forward. Plainclothes officers in gas masks yanked down banners for the second time in a day.
The Associated Press contributed to this report.