Protests spread in southern Syria Tuesday as hundreds of people marched to demand reforms in a previously peaceful village, witnesses and activists said.
In a nearby city, troops and protesters faced off outside a mosque where demonstrators have taken shelter.
A group named "United Arab Tribes in Syria" posted a message online in which it declared a "revolution against the Syrian regime."
The government sought to contain the first serious intrusion of the Arab world's political unrest by firing the governor of the southern province of Deraa, where security forces killed seven protesters in the main city of Deraa over the weekend.
The governor's dismissal failed to quell popular anger and the protests reached the village of Nawa, where hundreds of people marched demanding reforms, an activist told The Associated Press.
The activist said troops were trying to reach the mosque in Deraa's historic center where protesters have sought protection. He said protesters placed large rocks in the streets near the al-Omari mosque to block the troops.
There was a heavy security presence and most of the shops were closed elsewhere in the old quarter of Deraa, witnesses said.
A clip posted on YouTube showed several hundred villagers in Sanamein, near Deraa, chanting "Freedom!" while another showed dozens gathered in the Hajar Aswad neighborhood of the capital.
Syrian activists who reported the protests said they took place Monday evening. The activists spoke on condition of anonymity because they feared government reprisals. The authenticity of the videos could not be independently verified.
Protests also spread Monday to the towns of Jasim and Inkhil near Deraa, witnesses said.
Many demonstrators demanded the departure of provincial governor Faisal Kalthoum after security forces used tear gas, water cannons and later live ammunition to disperse the crowds, which first gathered on Friday.
Enraged residents then set fire to several government buildings in a startling outburst of unrest in one of the Middle East's most repressive countries.
Kalthoum was fired on Tuesday, a Syrian official said, speaking on condition of anonymity in line with regulations barring him from being identified by name. Daraa residents accused Kalthoum - in office since 2006 - of corruption and during a demonstration Monday many chanted, "The people want to bring down the governor!"
The Damascus-based National Organization for Human Rights in Syria said authorities were continuing "arbitrary and random arrests" in areas that witnessed protests, adding that families of detainees said none have been freed.
Like most Syrian cities, Deraa is home to ultra-orthodox Sunni Muslims.
In 2006, security agents arrested 16 Syrians during a three-day sweep in Deraa province, accusing them of membership to the banned Muslim Brotherhood.
In Geneva, the UN's human rights office urged Syria to investigate the death of protesters in Deraa. Rupert Colville, a spokesman for the Geneva-based office, said the government "should carry out an independent, transparent and effective investigation into the killings."
Colville said Tuesday that protesters had the right to express their grievances and be heard by the government.
Syrian Vice President Farouk al-Sharaa was quoted by local television network Al Manar as saying Tuesday that Assad was "committed to continuing along the path of reform and modernization in Syria. Assad cannot be against any Syrian citizen."