Widespread protests erupted across Syria on Friday, suggesting that a deadly military crackdown focused on the central city of Hama this week has served only to fuel anger with the government, not to deter people from taking to the streets.

Tens of thousands of Syrians poured out of mosques after noontime prayers to join demonstrations and express their fury over the violence in Hama, where human rights groups say at least 200 people have been killed since tanks rolled into the city Sunday to crush a four-month-old uprising against the regime led by President Bashar al-Assad.

The Local Coordination Committees, a group that organizes and reports on protests, said at least 15 people died when security forces opened fire on demonstrators, 11 of them in suburbs of the capital, Damascus, that have proved stubbornly resistant to multiple efforts to quell dissent.

With Hama under military lockdown and another former protest center, the eastern town of Deir el-Zour, also overrun by security forces, the total number of people on the streets was not as large as on many previous Fridays, the day on which demonstrations typically occur. The protests in Hama in recent weeks had drawn hundreds of thousands of people, according to activists and video footage, turning the city into a symbol of possibility for people struggling to gain momentum for the protest movement elsewhere in Syria.

At least 10 tanks were positioned in Hama’s central al-Assi square, where the massive protests had previously been centered, and residents said they were trapped indoors for a third consecutive day by rooftop snipers who opened fire on anything that moved.

Nonetheless, a small group of demonstrators attempted to stage a protest in the narrow back alleys of the old city, said Saleh al-Hamawi, an activist contacted by satellite telephone who lives next to the square. They were dispersed after security forces opened fire and killed three of them, he said.

“It's impossible to move,” Hamawi said. “There are bodies lying in the street, but we can’t reach them. We still don’t know the total number of killed people, but we are always hearing very heavy gunfire.”

Some of the largest demonstrations Friday occurred in the northern province of Idlib and the southern province of Daraa, the targets of earlier tank-led assaults, suggesting that the stretched Syrian security forces are unable to crack down everywhere at once and pointing to the resilience of the protest movement even in those areas subjected to the worst violence of the uprising.

Syrian state television broadcast footage of the damage inflicted in recent days on Hama, showing pictures of burned buildings, damaged cars and rubble-strewn streets, which the government says had been taken over by “armed gangs.”

“Syrian Arab Army units are working to restore security, stability and normal life to Hama after armed terrorist groups perpetrated acts of sabotage and killing,” the official news agency SANA reported. It said 20 Syrian soldiers were killed in the assault.

But the few outsiders who have managed to visit the city, including the U.S. ambassador, Robert Ford, have reported that they saw no evidence the protesters there were armed. The attack on Hama has drawn widespread international condemnation, including, crucially, from Syria’s ally Russia, which has until now blocked action against Assad’s government at the United Nations.

The assault came as part of a wider crackdown after activists pledged to escalate their protests during the Muslim holy month of Ramadan, which began Monday. The evening prayers held after people break their daily fast have now become the main focus of protest activity, turning demonstrations into a nightly event. Thousands more people were reported by activists to be streaming onto the streets in towns and cities around the country Friday night.