An opposition fighter holds a rocket launcher in front of a provincial government office with a bullet-riddled image of President Bashar Assad in Hama, Syria. (Ghaith Alsayed / Associated Press)

Syrian President Bashar Assad has left the country to an unknown location as his government collapses following a lightning offensive by opposition fighters who have since taken control of the capital Damascus, news agencies reported early on Sunday.

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 — who heads the Britain-based Syrian Observatory for Human Rights, an opposition war monitor — told the Associated Press that Assad took a flight Sunday out of Damascus.

Two senior Syrian army officers also told Reuters that Assad flew out of Damascus Sunday for an unknown destination.

Syrian Prime Minister Mohammed Ghazi Jalali said 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.

The rebels had already seized the cities of Aleppo and Hama, as well as large parts of the south in an offensive that began on November 24.

According to NPR, the advances in the past week were by far 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, led by the Hayat Tahrir al-Sham group, or HTS, have met little resistance from the Syrian army.