BEIRUT - Thousands of Syrians flooded the streets across the country Friday, defying an unrelenting government crackdown that has failed to crush a two-month uprising against the country's authoritarian regime. Human rights activists said security forces opened fire, killing at least 27 people, including a 10-year-old boy.

Friday's turnout -- and the now-familiar, deadly response by the regime -- was the latest sign the conflict could be moving toward a dangerous stalemate with neither side able to tip the scales. President Bashar Assad's forces have unleashed tanks and snipers and made thousands of arrests to break the revolt, but protesters continue to face down security forces.

Protesters insisted their movement was growing and they would not be bowed.

"We, as young activists, are very optimistic," said a protest organizer in the capital, which saw at least four separate demonstrations Friday -- a significant increase from recent rallies in Damascus, at the heart of the Assad regime's power. Like most protesters contacted by The Associated Press he asked that his name not be used for fear of government reprisals.

Assad has shrugged off U.S. calls to step aside as well as a new round of sanctions targeting him and top aides, suggesting mounting international pressure will not force an end to a crackdown that human rights groups say has killed at least 900 people since mid-March.

Friday's crushing security response came despite calls a day earlier from U.S. President Barack Obama that Assad should lead his country to democracy or "get out of the way." Syria's official news agency said Obama's admonition amounted to "incitement."

The revolt has posed the most serious challenge to the Assad family's 40-year ruling dynasty. When the uprisings sweeping the Arab world reached Syria in mid-March, it appeared to take Assad by surprise. The Syrian leader had enjoyed a degree of popularity in large part because of his anti-Israel views and the reputation of being the only Arab leader willing to stand up to the Jewish state. But his regime's response to the uprising appears to have eroded much of that goodwill.

Still, protesters have yet to bring out the sustained, daily, massive protests that brought down the leaders in Egypt and Tunisia, and analysts say it's too soon to say whether Assad can survive the upheaval.

Assad's sweeping campaign of intimidation, mass arrests and heavy security kept crowds last week below earlier levels seen during the uprising. But larger and more widespread marches Friday suggest that opposition forces could be trying to regroup.

"There were large numbers from the south to the north to the suburbs, and there were protests in besieged cities and towns," said Rami Abdul-Rahman, director of the Syrian Observatory for Human Rights.

"Despite the heavy security and military presence in almost all these places, people staged protests calling for freedom. This is very significant," he said.

Witnesses reported protests in the central cities of Homs and Hama, the capital of Damascus and its suburbs, and the Mediterranean ports of Banias and Latakia. In the northern city of Aleppo, Syria's second-largest city, security forces using batons quickly dispersed dozens of demonstrators, an activist said.

Human rights activist Mustafa Osso said the army deployed tanks around the northern town of Maaret al-Numan, which has seen intense protests. The Local Coordination Committees in Syria, which help organize the protests, said dozens of people were wounded in the town and hospitals were calling for blood donations.

In the predominantly Kurdish northeastern town of Qamishily, some 5,000 people marched chanting "what a shame, the peaceful (protesters) are faced with fire," Osso said. He added that some 4,000 marched in the nearby town of Derbasiya while more than 2,000 protested in the village of Amouda. He said demonstrators dispersed peacefully.

Friday's death toll was reported by the Syrian Observatory for Human Rights. The group said 10 people were killed in Homs, 11 in Maaret al-Numan, one in Latakia, two in the northeastern town of Deir el-Zour, one each in the southern villages of Sanamein and Harra and one in the Damascus suburb of Daraya.

A 10-year-old boy was among the dead in Homs, Osso said.

Syria has banned foreign journalists and prevented local reporters from covering trouble spots, making it nearly impossible to independently verify witness accounts.

Syria's state-run TV blamed "armed groups who took advantage of peaceful gatherings," for the violence.

In Brussels, a senior European Union official said Friday that EU foreign ministers will consider next week whether to tighten sanctions against the Syrian regime.

Also Friday, leading Sunni Muslim cleric Sheik Karim Rajeh, the imam of Damascus's Al-Hassan mosque, said he will no longer lead Friday sermons because security forces have been preventing people from going to prayers.

The weekly demonstrations mostly kick off after prayers.