Sri Lanka's Prime Minister Ranil Wickremesinghe was sworn in Friday as interim president until parliament elects a successor to former President Gotabaya Rajapaksa, who fled abroad and resigned after mass protests over the country’s economic collapse.

Lawmakers were to convene Saturday to begin choosing a new leader who would serve the remainder of Rajapaksa's term, which ends in 2024.

A tenuous calm returned to the capital of Colombo on Thursday after protesters who had occupied government buildings retreated, but with the political opposition deeply fractured, a solution to Sri Lanka’s many problems seemed no closer.

As people celebrated in the streets, Parliament Speaker Mahinda Yapa Abeywardana promised a swift and transparent political process that should be done within a week.

The new president could appoint a new prime minister, who would then have to be approved by parliament. After Rajapaksa resigned, pressure on the prime minister was rising.

"There is a big difference between protesters and insurgents. We will take legal action against insurgents," he said.

Wickremesinghe became acting president after Rajapaksa fled Sri Lanka on Wednesday, flying first to the Maldives and then to Singapore. The prime minister's office said Wickremesinghe was sworn in Friday as interim president.

Meanwhile, Sri Lanka’s opposition leader, who is seeking the presidency, vowed to "listen to the people" and to hold Rajapaksa accountable, in an interview with The Associated Press (AP).

"That’s what we should do. That is our function – catching those who looted Sri Lanka. That should be done through proper constitutional, legal, democratic procedures," Premadasa said.

Sri Lanka has run short of money to pay for imports of basic necessities such as food, fertilizer, medicine and fuel for its 22 million people. Its rapid economic decline has been all the more shocking because, before this crisis, the economy had been expanding, with a growing, comfortable middle class.

The protests underscored the dramatic fall of the Rajapaksa political clan that has ruled Sri Lanka for most of the past two decades.

Jeewantha Peiris, a Catholic priest and protest leader, said the country had "come through a hard journey."

"We are happy as a collective effort because this struggle of Sri Lanka was participated by all the citizens of Sri Lanka, even diaspora of Sri Lanka," he said.

Protesters cooked and distributed milk rice – a food Sri Lankans enjoy to celebrate victories – after Rajapaksa resigned. At the main protest site in front of the president’s office in Colombo, people welcomed his resignation but insisted Wickremesinghe also should step aside.

Sri Lanka remains a powder keg, with its economy in ruins. And the military warned Thursday that it had powers to respond in case of chaos – a message some found ominous.

Abeywardana, the speaker of parliament, urged the public to "create a peaceful atmosphere in order to implement the proper parliamentary democratic process and enable all members of parliament to participate in the meetings and function freely and conscientiously."

Sri Lanka is seeking help from the International Monetary Fund (IMF) and other creditors, but its finances are in such bad shape that even obtaining a bailout has proven difficult, Wickremesinghe recently said.

The protesters accuse Rajapaksa and his powerful political family of siphoning money from government coffers and of hastening the country’s collapse by mismanaging the economy. The family has denied the corruption allegations, but Rajapaksa acknowledged that some of his policies contributed to Sri Lanka's meltdown.

Maduka Iroshan, 26, a university student and protester, said he was "thrilled" that Rajapaksa had quit because he "ruined the dreams of the young generation."

Months of protests reached a frenzied peak last weekend when demonstrators stormed the president’s home and office and Wickremesinghe's official residence. On Wednesday, they seized his office.

Images of protesters inside the buildings – lounging on elegant sofas and beds, posing at officials’ desks and touring the opulent settings – captured the world’s attention.

The demonstrators initially vowed to stay until a new government was in place, but they shifted tactics Thursday, apparently concerned that an escalation in violence could undermine their message following clashes outside parliament that left dozens injured.

Protester Mirak Raheem noted that the lack of violence was important, though their work was far from over.

"This is really something amazing, the fact that it happened on the back of largely peaceful protest. But obviously, this is just a beginning," Raheem said, citing work to rebuild the economy and restore public confidence in the political system.

Rajapaksa and his wife slipped away in the night aboard a military plane early Wednesday. On Thursday, he went to Singapore, according to the city-state’s foreign ministry. It said he had not requested asylum, and it was unclear if he would stay or move on. He previously obtained medical services there, including undergoing heart surgery.

Since Sri Lankan presidents are protected from arrest while in power, Rajapaksa likely wanted to leave while he still had constitutional immunity and access to the plane.

As a military strategist whose campaign helped end the country’s 26-year civil war, Rajapaksa and his brother, who was president at the time, were hailed by the island’s Sinhalese majority. Despite accusations of wartime atrocities, including ordering military attacks on ethnic Tamil civilians and abducting journalists, Rajapaksa remained popular among many Sri Lankans. He has continually denied the allegations.