Mounting protests in Tunisia have unseated the North African country's President Zine El Abidine Ben Ali, after more than two decades of iron-fisted rule.

The uprising -- which was unprecedented in a region dominated by autocratic leaders -- culminated Friday after weeks of escalating unrest.

Thousands of demonstrators marched into the capital of Tunis demanding the ouster of Ben Ali, whose leadership had come under fire due to ever-present corruption, persistently high unemployment and autocratic rule.

"Ben Ali, out!" and "Ben Ali, assassin!" the protesters hollered as they made their way towards the Interior Ministry.

The government claims that at least 23 people were killed in rioting, while opposition members placed the death toll much higher.

As police clashed with protesters in the streets of the capital, Tunisian Prime Minister Mohammed Ghannouchi appeared on state television to announce he was assuming power, hours after the president declared a state of emergency.

"I take over the responsibilities temporarily of the leadership of the country at this difficult time to help restore security," Ghannouchi said. "I promise ... to respect the constitution, to work on reforming economic and social issues with care and to consult with all sides."

Prior to the prime minister's statement, Ben Ali had announced that he would dismiss his government and call new legislative elections.

Many Tunisians rejoiced at the departure of the 74-year-old president, who quashed dissent during 23 years in power, jailed opposition figures and kept a tight rein on the media.

"My first reaction is relief," said Dr. Souha Naija, a radiologist at a local hospital.

"He's gone ... I finally feel free," she said. "They got the message. The people don't want a dictator."

But there were also fears of what the future would hold, as well as about the role the military will play during the transition. Ben Ali stepped down temporarily, and his whereabouts were unknown.

"It's ambiguous," Naija said.

Meanwhile, U.S. President Barack Obama issued a statement applauding the courage and dignity of the Tunisians who were protesting, and pushed for all parties to refrain from violence.

Tunisian air space was closed on Friday, and it remained unclear whether his departure from power would restore order.

Foreign tourists are being warned about the high level of unrest in the country, with tour operator Thomas Cook asking its 3,800 European customers to leave the country.

As of Thursday, Foreign Affairs was advising Canadians to avoid all non-essential travel to Tunisia because of the "deteriorating security situation in many parts of the country." U.S. and European governments have issued similar alerts.

Ben Ali usurped power in a bloodless palace coup in 1987. He deposed Habib Bourguiba, whose formal title was president-for-life and who took over when Tunisia achieved independence from France in 1956.

Ben Ali said he was taking over from Bourguiba due to "incompetence" because his predecessor had become too old, senile and sick to govern.

At the time, he pledged to "open the horizons to a truly democratic and evolved political life."

With files from The Associated Press