BEIRUT, Lebanon - Residents used automatic rifles and rocket-propelled grenades to repel advancing government troops in central Syria, putting up a fierce fight Monday for the first time in their two-month-old revolt against President Bashar al-Assad's autocratic regime.

The escalation raised fears that the popular uprising might be moving toward a Libya-style armed conflict.

Until now, the opposition against Assad has taken the form of peaceful protests by unarmed demonstrators, though authorities have alleged, without offering solid proof, that it was being led by armed gangs and propelled by foreign conspiracies.

Activists said residents of Talbiseh and Rastan, towns under attack since Sunday in central Homs province, decided to fight back with automatic rifles and rocket-propelled grenades, and at least four civilians were killed.

"They felt that they cannot sit back anymore and pray for God to help them," said one Homs resident with wide connections in the province. Like all residents contacted by the Associated Press, he spoke on condition of anonymity for fear of reprisals.

Two more bodies were found Monday in the area of Bab Amro cemetery, raising the death toll from the two-day crackdown in Syria's turbulent heartland to 15, said the Local Coordination Committees in Syria, which helps organize and document the protests. State media said four soldiers were killed.

"The army is facing armed resistance and is not able to enter the two towns," the Homs resident said. "The army is still outside the towns, and I was told that army vehicles, including armored personnel carriers, were set on fire."

A second activist confirmed that residents had fought back but said it had involved individual residents protecting themselves, as opposed to an organized armed resistance with an overall command structure.

"The protests began peacefully, but the practices of security forces that humiliated the people eventually led to the use of arms," he said. He said it was common for Syrians to have light weapons such as rifles in their homes, adding that in recent years weapons have been smuggled in from neighboring countries such as Lebanon and Iraq.

Homs has seen some of the biggest demonstrations against Assad since protests broke out in southern Syria in March and spread across the country - posing the most serious challenge to the Assad regime's 40-year rule.

Human-rights groups say more than 1,000 people have been killed in the regime's crackdown, which has drawn condemnation and sanctions from the United States and European Union.