Tunisia, often touted as the lone success story of the Arab spring revolutions a decade ago, is facing a critical challenge to its fledgling democracy after its president, Kais Saied, suspended parliament and dismissed his prime minister in what critics described as a coup.

Saied, an independent without a party behind him, announced he was invoking an emergency article of Tunisia’s constitution on Sunday night after a day of violent protests against the country’s biggest party, the Islamist-inspired Ennahda movement.

Tunis was flooded with celebrating crowds waving flags, letting off fireworks and honking car horns after Saied’s declaration, in scenes reminiscent of the 2011 protests which toppled the country’s longtime autocratic ruler, Zine El Abidine Ben Ali.