Ousted Syrian President Bashar Assad has been granted refuge in Russia and is currently Moscow, Russian state news agency TASS reported, citing the Kremlin.
Islamist-led rebels swept into Damascus early on Sunday, forcing Assad to flee and bringing an end to more than 50 years of his family's rule.
The victorious rebel groups declared a curfew beginning 4:00 pm local time (1:00pm GMT) for thirteen hours, until 5:00 am Wednesday.
Crowds celebrated across the country and some toured Assad's home.
Abu Mohammed al-Jolani, leader of the Islamist Hayat Tahrir al-Sham group (HTS) that led the rebel advance addressed the nation from the Umayyad Mosque in Damascus.
"This victory, my brothers, is historic for the region," he said.
US President Joe Biden said Washington will "engage with all Syrian groups" during the transition of power, adding that Assad should be held accountable for his actions.
Several other world leaders hailed the fall of Assad's dictatorship.
"This historic change in the region offers opportunities but is not without risks," European Commission President Ursula von der Leyen said.
US military reports mutliple strikes on 'ISIS camps and operatives'
The US Central Command (CENTCOM) responsible for the Middle East and other areas said its forces conducted "dozens of precision airstrikes targeting known ISIS camps and operatives in central Syria" on Sunday, using another common acronym for the so-called "Islamic State" group.
"The strikes against the ISIS leaders, operatives, and camps were conducted as part of the ongoing mission to disrupt, degrade and defeat ISIS," CENTCOM said.
It said this was not only to prevent the terror group to conduct external operations, but also "to ensure that ISIS does not seek to take advantage of the current situation to reconstitute in central Syria."
CENTCOM said its aircraft, including F-15 combat jets, A-10 close air support planes, and the huge, high-altitude B-52 bomber, struck a total of more than 75 targets.
It said there was no preliminary indication of civilian casualties, and made no mention of combatant casualties.
"There should be no doubt — we will not allow ISIS to reconstitute and take advantage of the current situation in Syria," said General Michael Erik Kurilla. "All organizations in Syria should know that we will hold them accountable if they partner with or support ISIS in any way."
UN Security Council to meet over Syria
Russia has requested an emergency session of the UN Security Council to be held Monday, after rebels seized control of Damascus and overthrew President Bashar Assad.
The meeting is scheduled for 3:00 pm (2000 GMT). Multiple diplomatic sources told the AFP and DPA news agencies that the meeting would take place behind closed doors.
Rebel groups made sudden advances over the last 11 days, eventually toppling Assad's government as they moved on to Damascus.
