The latest:

• Rebels appear on state TV to announce they ousted '"tyrant."
• Syrians storm presidential palace, tearing up portraits of the toppled president.
• Syrian PM says he lost communication with Bashar al-Assad late Saturday.
• UN envoy speaks of moving toward "united and peaceful Syria."

The Syrian government collapsed early Sunday, falling to a lightning rebel offensive that seized control of the capital of Damascus and sent crowds into the streets to celebrate the end of the Assad family's 50 years of iron rule.

Syrian state television aired a video statement by a group of men saying that President Bashar al-Assad, referred to as a "tyrant," a had been overthrown and all "unjustly detained" prisoners had been set free.

The man who read the statement said the opposition group, known as the Operations Room to Conquer Damascus, called on all rebel fighters and citizens to preserve the institutions of "the free Syrian state."

The statement emerged hours after the head of a Syrian opposition war monitor said Assad had left the country for an undisclosed location, fleeing ahead of insurgents who said they had entered Damascus following a remarkably swift advance across the country.

Many of the capital's residents were in disbelief at the speed at which Assad lost his hold on the country after nearly 14 years of civil war that killed hundreds of thousands of people, displaced half the country's pre-war population of 23 million and drew in several foreign powers.

Celebrations erupt across the capital

As daylight broke over Damascus, crowds gathered to pray in the city's mosques and to celebrate in the squares, chanting "God is great." People also chanted anti-Assad slogans and honked car horns. Teen boys picked up weapons that had apparently been discarded by security forces and fired them in the air.

Revellers filled Umayyad Square in the city centre, where the Defence Ministry is located. Men fired celebratory gunshots into the air and some waved the three-starred Syrian flag that predates the Assad government and was adopted by the revolutionaries.

A few kilometres away, Syrians stormed the presidential palace, tearing up portraits of the toppled president.

Soldiers and police officers left their posts and fled, and looters broke into the Defence Ministry. Videos from Damascus showed families wandering into the presidential palace, with some emerging carrying stacks of plates and other household items.

"I did not sleep last night, and I refused to sleep until I heard the news of his fall," said Mohammed Amer Al-Oulabi, 44, who works in the electricity sector.

"From Idlib to Damascus, it only took them [the opposition forces] a few days, thank God. May God bless them, the heroic lions who made us proud."

Syria's al-Watan newspaper, which was historically pro-government, wrote: "We are facing a new page for Syria. We thank God for not shedding more blood. We believe and trust that Syria will be for all Syrians."

• What questions do you have about Syria and the fall of Bashar al-Assad? Are you a Syrian refugee in Canada — what's your reaction? Leave your questions and comments here to be part of Cross Country Checkup today at 4 p.m. ET.

The newspaper added that media workers should not be blamed for publishing government statements in the past.

"We only carried out the instructions and published the news they sent us," it said. "It quickly became clear now that it was false."

A statement from the Alawite sect — to which Assad belongs and which has formed the core of his base — called on young Syrians to be "calm, rational and prudent and not to be dragged into what tears apart the unity of our country."

Assad's whereabouts unknown

Syrian Prime Minister Mohammed Ghazi Jalali said in a video statement that the government was ready to "extend its hand" to the opposition and turn its functions over to a transitional government. A video shared on Syrian opposition media showed a group of armed men escorting him out of his office and to the Four Seasons hotel on Sunday.

The prime minister had earlier told the Al Arabiya news network that he does not know where Assad and the defence minister are. He said he lost communication with Assad late Saturday.

Rami Abdurrahman of the Syrian Observatory for Human Rights told The Associated Press that Assad took a flight Sunday from Damascus.

A senior diplomat from the United Arab Emirates, which had sought to rehabilitate Assad's image and has welcomed high-profile exiles in recent years, declined to comment on his whereabouts when asked by reporters at a conference in Bahrain.

WATCH | Why the war in Syria reignited: 

Why the war in Syria just reignited

The civil war in Syria has reignited after years of lying dormant, with a coalition of opposition forces swiftly taking control of a number of major cities. CBC’s Chris Brown breaks down how the situation unravelled and the key players fighting for control.

Anwar Gargash said Assad's destination at this point is a "footnote in history," comparing it to the long exile of German Kaiser Wilhelm II after World War I.

Assad has been accused of war crimes and crimes against humanity during the war, including a 2013 chemical weapons attack on the outskirts of the capital.

There was no immediate comment from Iran, which had been Assad's staunchest supporter. The Iranian Embassy in Damascus was ransacked after apparently having been abandoned. AP footage showed broken windows and documents scattered in the entryway.

Opposition forces had not reached Damascus since 2018, when Syrian troops recaptured areas on the outskirts of the capital following a years-long siege.

Calls for an orderly transition

The rebel advances since Nov. 27 were the largest in recent years, and saw the cities of Aleppo, Hama and Homs fall in a matter of days as the Syrian army melted away. Russia, Iran and Lebanon's Hezbollah militant group, which provided crucial support to Assad throughout the uprising, abandoned him in the final days as they reeled from other conflicts.

The rebels are led by the Hayat Tahrir al-Sham group, or HTS, which has its origins in al-Qaida and is considered a terrorist organization by the United States and the United Nations.

Its leader Abu Mohammed al-Golani has sought to remake the group's image, cutting ties with al-Qaeda, ditching hard-line officials and vowing to embrace pluralism and religious tolerance. HTS set up a "salvation government" in 2017 to administer a large region in northwestern Syria under its control.

"Golani has made history and sparked hope among millions of Syrians," said Dareen Khalifa, a senior adviser with the International Crisis Group and an expert on Syrian groups.

"But he and the rebels now face a formidable challenge ahead. One can only hope they rise to the occasion."

The UN's special envoy for Syria, Geir Pedersen, called Saturday for urgent talks in Geneva to ensure an "orderly political transition." Russian Foreign Minister Sergey Lavrov, whose country is Assad's chief international backer, said he feels "sorry for the Syrian people."

"The challenges ahead remain immense and we hear those who are anxious and apprehensive," Geir said in a statement.

"Yet this is a moment to embrace the possibility of renewal. The resilience of the Syrian people offers a path toward a united and peaceful Syria."

Warning about radicals taking control

German Foreign Minister Annalena Baerbock expressed understanding for the relief Syrian people felt after the fall of Assad's government, but warned that "the country must not now fall into the hands of other radicals."

"Several hundred thousand Syrians have been killed in the civil war, millions have fled," Baerbock said in a statement emailed by her office Sunday. "Assad has murdered, tortured and used poison gas against his own people. He must finally be held accountable for this."

Baerbock also called "on the parties to the conflict to live up to their responsibility for all Syrians."

"This includes the comprehensive protection of ethnic and religious minorities such as Kurds, Alawites or Christians and an inclusive political process that creates a balance between the groups," the German foreign minister said.

The Gulf nation of Qatar, a key regional mediator, hosted an emergency meeting of foreign ministers and top officials from eight countries with interests in Syria late Saturday. The participants included Iran, Saudi Arabia, Russia and Turkey.

Majed bin Mohammed al-Ansari, Qatar's foreign ministry spokesperson and an adviser to the prime minister, told reporters that they agreed on the need "to engage all parties on the ground," including the HTS, and that the main concern is "stability and safe transition."

The Israeli military said Sunday it has deployed forces in a demilitarized buffer zone along its northern frontier with Syria following the rebel offensive there.

The military, which said it also sent troops to "other places necessary for its defence," said the deployment was meant to provide security for residents of the Israeli-annexed Golan Heights. Israel captured the territory in the 1967 Mideast war and the international community, except for the United States, views it as occupied.

WATCH | Civilians at risk as Syria violence flares, UN chief says:

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United Nations Secretary General António Guterres says after years of conflict in Syria, it is 'high time' for all parties to engage seriously and chart a path to resolving the long-running crisis.