The head of a Syrian opposition war monitor said early Sunday that President Bashar Assad left the country for an undisclosed location, fleeing ahead of insurgents who said they had entered Damascus after a stunning advance across the country.  

Syrian opposition fighters said early Sunday local time that they had entered Damascus and residents of the capital reported the sounds of gunfire and explosions. 

Rami Abdurrahman of the Syrian Observatory for Human Rights told the Associated Press that Assad took a flight Sunday from Damascus.  Two senior Syrian army officers also told Reuters that Assad flew out of Damascus Sunday for an unknown destination. 

The Syrian army notified officers that Assad’s rule had ended, Reuters reported.  

Syrian Prime Minister Mohammed Ghazi Jalali said early Sunday that the government was ready to “extend its hand” to the opposition and hand over its functions to a transitional government.

“I am in my house and I have not left, and this is because of my belonging to this country,” Jalili said in a video statement. He said he would go to his office to continue work in the morning and called on Syrian citizens not to deface public property.

He did not address reports that Assad had fled. 

The pro-government Sham FM radio reported that Damascus airport was evacuated and all flights halted.

The insurgents also announced they had entered the notorious Saydnaya military prison north of the capital and “liberated our prisoners” there.

Damascus was expected to fall, three U.S. officials had previously earlier told CBS News, after Syrian insurgents surrounded the capital in a swiftly moving offensive that first began Nov. 27. Syrian insurgents also claimed early Sunday to have captured the key central city of Homs. 

Iranian forces who’d been defending Assad had “pretty much” evacuated from Syria, the U.S. officials said earlier Saturday. 

Syrian insurgents reached the suburbs of Damascus on Saturday as part of a rapidly moving offensive that has seen them take over some of Syria’s largest cities, opposition activists and a rebel commander said Saturday.

The advances in the past week were among the largest in recent years by opposition factions, led by a group that has its origins in al-Qaida and is considered a terrorist organization by the U.S. and the United Nations. In their push to overthrow Assad’s government, the insurgents have met little resistance from the Syrian army.

The approaching fighters are led by the most powerful insurgent group in Syria, Hayat Tahrir al-Sham, or HTS, along with an umbrella group of Turkish-backed Syrian militias called the Syrian National Army. Both have been entrenched in the northwest.    

For the first time in the country’s long-running civil war, the government had control of only three of 14 provincial capitals: Damascus, Latakia and Tartus.    

Rami Abdurrahman, who heads the Britain-based Syrian Observatory for Human Rights, an opposition war monitor, said insurgents were active in the Damascus suburbs of Maadamiyah, Jaramana and Daraya. He added that opposition fighters on Saturday were also marching from eastern Syria toward the Damascus suburb of Harasta.

A commander with the insurgents, Hassan Abdul-Ghani, posted on the Telegram messaging app that opposition forces have started carrying out the “final stage” of their offensive by encircling Damascus. He added that insurgents were headed from southern Syria toward Damascus.

Ghani said early Sunday local time that insurgent forces had “fully liberated” Homs, Syria’s third-largest city, Reuters reported, as government forces had supposedly abandoned the city. If they have indeed captured Homs, they would cut the link between Damascus, Assad’s seat of power, and the northern coastal region where the president enjoys wide support.  

His chief international backer, Russia, is busy with its war in Ukraine, and Lebanon’s powerful Hezbollah, which at one point sent thousands of fighters to shore up his forces, has been weakened by a yearlong conflict with Israel. Iran, meanwhile, has seen its proxies across the region degraded by Israeli regular airstrikes. The Israel Defense Forces said on Saturday that after armed individuals carried out an attack at a U.N. post in the Hader area, their troops were currently assisting U.N. forces in repelling the attack. 

On Saturday, President-elect Donald Trump commented on the situation on Truth Social, saying, “THE UNITED STATES SHOULD HAVE NOTHING TO DO WITH IT. THIS IS NOT OUR FIGHT. LET IT PLAY OUT. DO NOT GET INVOLVED!”

Three U.S. officials told CBS News that the al-Assad family’s reign that started in 1971 appears to be ending.

“The United States is not going to…militarily dive into the middle of a Syrian civil war,” White House national security adviser Jake Sullivan told an audience at the Reagan National Defense Forum, an annual gathering of national security officials, defense firms and lawmakers at the Ronald Reagan Presidential Library in Simi Valley, California. “What we are going to do is focus on the American national security priorities and interests.”

He said the U.S. would keep acting as necessary to keep the Islamic State — a violently anti-Western extremist group not known to be involved in the offensive but with sleeper cells in Syria’s deserts — from exploiting openings presented by the fighting.  

How the conflict reignited

Thousands of people were fleeing from the area amid the dramatic escalation in the civil war, which had simmered without major advances by either side for years until the rebels mounted a shock offensive about two weeks ago.

The capture of Homs was a major victory for the rebels, who have already seized the northern cities of Aleppo and Hama, as well as large parts of the south, in a lightning offensive. Analysts said rebel control of Homs would be a game-changer. Aleppo is Syria’s second-largest city. 

HTS leader Abu Mohammed al-Golani told CNN in an exclusive interview Thursday from Syria that the aim of the offensive is to overthrow Assad’s government.

The Syrian army withdrew from much of southern Syria on Saturday, leaving more areas of the country, including two provincial capitals, under the control of opposition fighters, the military and an opposition war monitor said. The redeployment away from the southern provinces of Daraa and Sweida came as Syria’s military sent large numbers of reinforcements to defend Homs. 

The Syrian army said in a statement earlier Saturday that it had carried out redeployment and repositioning in Sweida and Daraa after its checkpoints came under attack by “terrorists.” The army said it is setting up a “strong and coherent defensive and security belt in the area,” apparently to defend Damascus from the south.

Since Syria’s conflict broke out in March 2011, the Syrian government has been referring to opposition gunmen as terrorists.

In the gas-rich nation of Qatar, the foreign ministers of Iran, Russia and Turkey were scheduled to meet to discuss the situation in Syria. Turkey is a main backer of the rebels seeking to overthrow Assad.

Qatar’s top diplomat, Sheikh Mohammed bin Abdulrahman Al Thani, criticized Assad for failing to take advantage of the lull in fighting in recent years to address the country’s underlying problems. “Assad didn’t seize this opportunity to start engaging and restoring his relationship with his people,” he said.

Sheikh Mohammed said he was surprised by how quickly the rebels have advanced and said there is a real threat to Syria’s “territorial integrity.” He said the war could “damage and destroy what is left if there is no sense of urgency” to start a political process.

After the fall of the cities of Daraa and Sweida early Saturday, Syrian government forces remain in control of five provincial capitals — Damascus, Homs and Quneitra, as well as Latakia and Tartus on the Mediterranean coast.

Tartus is home to the only Russian naval base outside the former Soviet Union while Latakia is home to a major Russian air base.

On Friday, U.S.-backed fighters of the Kurdish-led Syrian Democratic Forces (SDF) captured wide parts of the eastern province of Deir el-Zour that borders Iraq as well as the provincial capital that carries the same name. The capture of areas in Deir el-Zour is a blow to Iran’s influence in the region as the area is the gateway to the corridor linking the Mediterranean to Iran, a supply line for Iran-backed fighters, including Lebanon’s Hezbollah.

With the capture of a main border crossing with Iraq by the SDF and after opposition fighters took control of the Naseeb border crossing to Jordan in southern Syria, the Syrian government’s only gateway to the outside world is the Masnaa border crossing with Lebanon.

contributed to this report.