Pro-democracy demonstrators streamed into the streets of cities across the Middle East on Friday, dramatizing the Arab world’s enduring hunger for change three months into a revolt that has toppled two presidents and challenged the region’s stultified political order.

Security forces in Syria killed at least four people in a suburb of the capital, Damascus, where violent clashes had erupted, according to a Syrian human rights activist with a list of victims’ names. But in most other instances, the protests — in Yemen, Egypt and Jordan, as well as Syria — were generally contained and peaceful.

Even so, the spectacle of crowds in four countries relentlessly shouting “Freedom!” suggested that many Arabs have shaken off the passivity and fear that for generations kept unrepresentative leaders in power in the region, home to 340 million people and a large part of the world’s oil reserves.

The protests in Syria, although relatively small, were the most widespread since unrest broke out there on March 18 with demands that President Bashar al-Assad’s Arab nationalist government expand civil liberties. Crowds took to the streets after midday prayers in demonstrations of varying intensity, in Daraa, Homs, Baniyas, Idlib, Qamishli, Damascus and the capital’s outlying Douma area.

Protest leaders had labeled Friday “Martyrs’ Day,” calling for widespread demonstrations to mark disappointment with Assad’s tough speech Wednesday, in which he rebuffed demands for repeal of Syria’s 48-year-old emergency law. The hated measure, which gives police broad powers, has been a key part of the many-tentacled security apparatus on which Assad — like his father before him — has relied to smother opposition.

Activists said the most violent clashes with security forces occurred in Douma. A protester reached by telephone there said security forces shot tear gas canisters and live ammunition toward protesters crowding the street.

“The police opened fire on any gathering they saw, no matter how big or how small,” said the witness, who declined to give his name for fear of reprisals.

A video posted on YouTube purporting to record the Douma protests showed hundreds of men walking through the streets pumping their fists and chanting: “The people of Syria are one. One! One! One!” In another, protesters seemed to be fleeing plumes of tear gas, their mouths and noses covered with scarves and surgical masks.

“The people want the fall of the regime,” they chanted.

The Obama administration issued a statement condemning the violence and saying it was not the answer to popular grievances. Assad “has a responsibility to promptly take concrete steps and actions that deliver on his promises and advance a meaningful reform agenda,” the statement said.

Several thousand protesters also pushed through the streets of Daraa, the windswept city on Syria’s border with Jordan where the revolt began. Since then, human rights groups have counted more than 60 people killed and dozens wounded. Security forces turned out in large numbers in Daraa on Friday, but there were no reports of shooting.

In Yemen, rival protests

In Sanaa, the Yemeni capital, tens of thousands of pro- and anti-government demonstrators took to the streets after noon prayers in peaceful rival demonstrations that were among the largest since popular unrest erupted there two months ago.

Soldiers and riot police swarmed Sanaa and a military helicopter buzzed overhead as supporters of embattled President Ali Abdullah Saleh gathered in Sabyeen Square, urging him to defy his critics and remain in power. Many said they worried that if the president steps down, the ensuing political chaos would destabilize the country, the region’s poorest.

“We want him to stay as president until he dies,” declared Hilal al-Salat, a tribal leader from the south-central governorate of Damar.

Outside Sanaa University, the headquarters of the rebellion, anti-government demonstrators called for an immediate end to Saleh’s 32-year-rule. People wearing paper bandannas emblazoned with the word “Leave” marched and chanted: “This Friday, Ali Abdullah. This is your last Friday.”

“We want the kind of international support seen in the revolutions in Egypt and Tunisia,” said Bandar al-Thabyani, a 33-year-old teacher. “We all want the same democracy as in the United States and Europe. We just want to be treated like human beings.”

In Egypt, calls for Mubarak trial

As many as 50,000 people filed into Cairo’s now-celebrated Tahrir Square for a demonstration that had been billed as a “million-man march.” Their goal, leaders said, was to “rescue the revolution” and protest what many here regard as an attempt to block genuine change following the ouster of President Hosni Mubarak on Feb. 11.

Since Mubarak stepped down, Egypt has been run by the Supreme Council of the Armed Forces. The generals have promised parliamentary and presidential elections before the end of the year. But in the meantime, they rule by decree and, free of control by civilian courts, arrest people and try them in military tribunals.

The momentum that propelled demonstrations in January seems to have petered out, and many of Egypt’s 80 million people say they long for a return to stability and normalcy that would permit the economy to get moving again. Against that background, the turnout Friday was small compared with the hundreds of thousands of people who filled the square in January.

Undeterred, protesters demanded the immediate trial of Mubarak and his associates. Highest on their list were Fathi Serour, the former speaker of parliament, Zakariya Azmi, head of the presidential palace under Mubarak, and Safwat Sharif, the former secretary general of Mubarak’s National Democratic Party.

“We came to stress the point that people can go back to the streets again if it’s needed,” said Noha Alawy, 28. “Everything now is so slow and so ambiguous.”

In Jordan, police keep order

In Jordan, roughly 1,500 demonstrators gathered after Friday prayers outside City Hall in the capital, Amman, to call for an end to corruption and greater freedom. Although a protester was killed at a rally last week, Friday’s demonstration was orderly, due in large part to a heavy deployment of riot police who separated anti-government protesters from a smaller cluster of supporters of King Abdullah II and his government.

Carrying a giant Jordanian flag, pro-democracy demonstrators chanted slogans demanding that corrupt officials be fired and lamenting their financial straits. “Oh my father, look what’s happening to me,” they chanted. “Poverty is killing me.”

Fadi Barghouti, a 24-year-old nurse who took part in the demonstration, said the protests in Jordan were part of a wave of demands for government accountability sweeping across the Middle East — and, she added, “the whole world.”

Correspondents Sudarsan Raghavan in Sanaa and Leila Fadel in Cairo and special correspondents Muhammad Mansour in Cairo, Sufian Taha in Amman and a special correspondent in Damascus contributed to this report.