Thousands of people took to Tunisia's streets Wednesday to protest the killing of a leading opposition figure, amid fears that radicals are threatening to derail the country's democratic transition.
Chokri Belaid, a leading member of the Popular Front, a leftist coalition formed last year, was shot as he was leaving his home in the capital, Tunis.
Police used teargas to disperse protesters who had jammed the main Habib Bourguiba boulevard in central Tunis, yelling "shame, shame" as they denounced Belaid's assassination.
The headquarters of the moderate, Islamist Ennahda party, which rules in an uneasy coalition with secularists, was attacked and set ablaze.
Other demonstrations continued across Tunisia - including in Sidi Bouzid, birthplace of the Arab Spring uprisings - in scenes reminiscent of the country's largely peaceful revolution two years ago.
Later Wednesday, the Popular Front said it was pulling out of the constituent assembly charged with writing a constitution. A spokesman said the group would also call for a general strike to protest Belaid's murder.
Tunisian President Moncef Marzouki canceled his planned trip to a summit in Cairo because of the killing.
Speaking before the European Parliament in Strasbourg, France, Mr. Marzouki said his country has many enemies who want the revolution to fail.
An array of politicians denounced Belaid's death, including Ennahda party chief Rached Ghannouchi, who said the killers wanted a "bloodbath" in Tunisia.