COLOMBO, SRI LANKA -- Sri Lanka's prime minister was sworn in Friday as interim president until Parliament elects a successor to Gotabaya Rajapaksa, who fled abroad and resigned after mass protests over the country's economic collapse.

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

A tenuous calm was restored in 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, Ranil Wickremesinghe, was rising.

In a televised statement, Wickremesinghe said he would initiate steps to change the constitution to curb presidential powers and strengthen Parliament, restore law and order and take legal action against "insurgents."

It was unclear to whom he was referring, although he said true protesters would not have gotten involved in clashes near Parliament on Wednesday night, when many soldiers reportedly were injured.

"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 by Chief Justice Jayantha Jayasuriya.

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.

The Rev. 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.

"I am happy that Gotabaya has finally left. He should have resigned earlier, without causing much problems," Velayuthan Pillai, 73, a retired bank employee, said as patriotic songs blared from loudspeakers.

"Ranil is a supporter of Gotabaya and other Rajapaksas. He was helping them. He also must go," he added.

Sri Lanka remains a powder keg, 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 and other creditors, but its finances are so poor 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," Raheem said. "But obviously this is just a beginning, that there is a longer journey in terms of the kind of work that has to be done, not just to rebuild the economy but to create public confidence in this 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 has 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.

A military strategist whose brutal campaign helped end the country's 26-year civil war, Gotabaya Rajapaksa and his brother, who was president at the time, were hailed by the island's Buddhist 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.

Correction:

This version corrects the name of Velayuthan Pillai. It is spelled Velayuthan, not Velauynatha.