More than 10,000 protesters poured onto the streets of Syria’s commercial hub, Aleppo, on Friday, a sign that a city that had remained relatively quiet as an uprising swept the country has been galvanized into activity.

The northern city’s large university was the focus of a similar demonstration Thursday, when crowds of students greeted a team of U.N. observers, dancing on the tops of the visitors’ cars and waving the flag of the protest movement from the rooftops.

On Friday, three major mosques were the center of protest, according to the British-based Syrian Observatory for Human Rights, with people streaming out of them after Friday prayers calling for the fall of President Bashar al-Assad.

Security forces responded to the visible surge in support for the peaceful protest movement with tear gas and bullets, although no deaths were reported. Activists said, however, that nine people died in violence elsewhere in the country.

Live footage streamed online showing the crowds in Aleppo’s streets was greeted with delight by opposition activists, who have been deeply demoralized by the continued strength of Syrian security forces and the failure of a U.N.-backed peace plan to resolve the 15-month crisis.

“The opposition had been waiting for a long time for such protests to unfold in Aleppo,” said Randa Slim, a researcher at the New America Foundation, “and it came at a moment when the momentum had shifted toward the government.”

Aleppo is a center for Syria’s business community and middle classes, who some analysts say have been a core support base for Assad because they benefited from economic reforms undertaken in recent years. That makes the apparent shift in attitude there highly symbolic, said Slim, who added that opposition groups had been coordinating plans for large protests for some time and that the U.N. monitors’ visit provided the right moment.

“The opposition and business community believed that as long as Aleppo was holding out, there was still hope for Assad to salvage his regime,” she said. “But now that there have been protests in Damascus and Aleppo, this will convince people that this is a one-way road away from Assad.”

Slim cautioned, however, that such a road could take years to travel.

Fawaz Gerges, a Middle East expert at the London School of Economics, said that the protests did not change the fact that the authorities and opposition have reached an apparent stalemate, with neither side able to win a battle that looks increasingly like a civil war.

Activists have reported dozens of deaths from days of heavy artillery fire on the central town of Rastan since armed opposition fighters killed more than 20 soldiers there earlier in the week. Those and other reports could not be confirmed independently because of Syrian reporting restrictions.

“The opposition is much more divided than we think, the security apparatus is cohesive, and still the regime subscribes to the idea that this is a security situation,” Gerges said. In an interview with Russian television this week, Assad said that the unrest was the work of terrorists and that there was no real domestic opposition.

The Norwegian head of the 260-member unarmed U.N. observer mission said Friday in the capital, Damascus, that only a political solution could halt the unrest.

“No volume of observers can achieve a progressive drop and a permanent end to the violence if the commitment to give dialogue a chance is not genuine from all internal and external actors,” Maj. Gen. Robert Mood said at a news conference.

He urged both sides to show “moral courage” and engage in dialogue, citing the example of South Africa’s Nelson Mandela.