The president had fled to the Maldives a day earlier amid mass protests in Sri Lanka.
One person has died and 84 others injured after protests rocked the Sri Lankan capital of Colombo on Wednesday, hospital officials have said.
The 26-year-old man died from breathing difficulties after police forces lobbied tear gas at protesters.
Sri Lanka’s Prime Minister Ranil Wickremesinghe was appointed acting president after President Gotabaya Rajapaksa fled the country.
But the decision triggered further protests demanding that he also resign.
Hospital officials at the Colombo National Hospital said the injuries came from protesters who were outside the prime minister’s office as well as those who were outside parliament later in the evening.
Police had fired tear gas at protesters who attempted to break down the gates of the prime minister’s office in Colombo, before finally making their way in. They later made their way towards parliament.
A military spokesperson told the BBC said that a soldier and police officer were amongst the injured, and alleged that an assault rifle with ammunition had been stolen by a protester and had not yet been recovered.
Early on Thursday, Sri Lanka imposed a new curfew, which would be in place from 12:00 on Thursday till 05:00 on Friday, said the government in a statement.
The protests come as Sri Lanka has been suffering from its worst economic crisis in decades.
Many blame the Rajapaksa administration for the crisis and see Mr Wickremesinghe, who became prime minister in May, as part of the problem.
In a television address late on Wednesday, Mr Wickremesinghe had called on protesters to leave his occupied office and other state buildings and co-operate with authorities.
He also told the military to do “whatever is necessary” to restore order.
His statement came hours after Mr Rajapaksa had fled to the Maldives – days after his official residence was stormed.
Mr Rajapaksa had pledged to resign by Wednesday, but is still yet to submit a formal letter of resignation.
The leader, who has enjoyed immunity from prosecution as president, is believed to have wanted to flee abroad before stepping down to avoid the possibility of arrest by the new administration.
The president’s departure threatens a potential power vacuum in Sri Lanka, which needs a functioning government to help dig it out of financial ruin.
Politicians from other parties have been talking about forming a new unity government but there is no sign they are near agreement yet. It’s also not clear if the public will accept what they come up with.
In a press statement on Wednesday, Mr Wickremesinghe’s team said he had asked the speaker of parliament to nominate a new prime minister “who is acceptable to both the government and opposition”.
Earlier on Monday, the main opposition leader Sajith Premadasa told the BBC he would be tilting for the presidency. But he – like Mr Wickremesinghe – lacks public support. There is also deep public suspicion of politicians in general.
The protest movement which has brought Sri Lanka to the brink of change also does not have an obvious contender for the country’s leadership.
Sri Lanka: The basics
- Sri Lanka is an island nation off southern India: It won independence from British rule in 1948. Three ethnic groups – Sinhalese, Tamil and Muslim – make up 99% of the country’s 22 million population.
- One family of brothers has dominated for years: Mahinda Rajapaksa became a hero among the majority Sinhalese in 2009 when his government defeated Tamil separatist rebels after years of bitter and bloody civil war. His brother Gotabaya, who was defence secretary at the time, is the current president but says he is standing down.
- Presidential powers: The president is the head of state, government and the military in Sri Lanka but does share a lot of executive responsibilities with the prime minister, who heads up the ruling party in parliament.
- Now an economic crisis has led to fury on the streets: Soaring inflation has meant some foods, medication and fuel are in short supply, there are rolling blackouts and ordinary people have taken to the streets in anger with many blaming the Rajapaksa family and their government for the situation.