Syrian President Bashar al-Assad was facing the most serious unrest of his 11-year tenure Thursday as anti-government protests in a southwestern city threatened to escalate after a deadly crackdown.

Having watched dissent convulse the region — two Arab autocrats have been ousted this year — the Syrian state has been taking no chances.

Even buying a can of spray paint is seen as a potentially subversive act, requiring an ID card that is registered with the government. Daraa, near the Jordanian border, became the center of the so-far-localized dissent after 15 children were arrested there this month for spray-painting walls with words that have rattled the Arab world: “The people want the fall of the regime.”

On Wednesday, security forces launched a pre-dawn raid in the city in which dozens of people were killed, according to witnesses and activists. Precise estimates of the death toll range from 15 to 51.

On Thursday, witnesses said, thousands of people gathered in the city to bury the dead, chanting, “Syria! Freedom!”

The killings have prompted calls for larger anti-government demonstrations on Friday, testing both Assad’s determination to quell the spirit of revolt by any means necessary and the will of Syrians fearful of chaos and civil war. The stakes are high for this nation of 22 million, which wields vast influence in neighboring Lebanon, has a decades-long territorial dispute with Israel and has been a crucial regional ally of Iran.

Authorities in the Syrian capital, Damascus, are also trying softer measures to contain the unrest. They have released the detained children and referred to some of those killed by Syrian security forces as “martyrs.” At a news conference Thursday, Bouthaina Shaaban, an adviser to Assad, announced a package of reforms that included opening up the media, allowing political parties and looking into lifting an emergency law in place since 1963.

State-run Syrian TV also announced that Assad had ordered the release of those detained in southern Syria in connection with the protests there. At least 92 people were detained in just the past week, according to the Syrian Human Rights League. Many others are in hiding.

But some observers say Assad — a 45-year-old, Western-educated doctor, who many Syrians still hope will deliver promised changes — will ultimately have to choose: use the historically brutal practices of Syria’s efficiently repressive security forces or implement serious reforms.

“Every Syrian is frightened, and they don’t want to be Iraq. That’s the cautionary tale — and the government has raised the banner of security and stability for the last 40 years,” said Joshua Landis, a Syria expert and director of the Center for Middle East Studies at the University of Oklahoma. “They’re hesitating, but it seems like there is a big hole in the dike here, and the fear factor is collapsing. The latest videos streaming out are horrifying; they’re very gruesome.”

The people will either react to the violence perpetrated by security forces in Daraa or submit to the fear, Landis said.

“The government is gambling that the people will be horrified by the prospect of Iraq, and the opposition hopes that the people will be emboldened and angered and go out Friday and demand change,” he said.

In a statement Thursday, the White House condemned what it called Syria’s “brutal repression of demonstrations, in particular the violence and killings of civilians” by security forces.

Assad is a close ally of Iran’s and a backer of militant groups that oppose Israel. Syria has also long seen itself as a proud Arab nation that stands up to the imperialist West and does not cave to Israeli demands.

As revolts spread throughout the Arab world, the unrest in Syria still seems 10 steps behind. It is virtually unheard-of in this one-party state for people to even joke about the ruling family. In cafes and restaurants, people speak about current events in code, never mentioning Assad by name.

Hafez al-Assad, the president’s father, came to power in 1971 after a coup. He suppressed dissent unapologetically, instilling the fear that is still pervasive here.

Bashar al-Assad took over after his father’s death in 2000. He promised to expand civic freedoms but never delivered, a failure many blame on the old guard loyal to his father. The younger Assad retains a measure of popularity.

The complaints that have generated unrest here are similar to those voiced across the region: the widening gap between rich and poor, the lack of freedom of expression and the 1963 emergency law, which authorizes arrests without warrants. There are no independent media outlets in Syria, although Assad has allowed satellite television and the Internet.

Calls for regime change are rare.

“I’m not sure that what we saw in other countries is the answer in Syria,” said Nadim Houry, a Human Rights Watch researcher based in Beirut. “Syria is a land of almost zero protests, and it is telling that there are these things happening.”

During a visit to Tel Aviv to meet with Israeli officials, Defense Secretary Robert M. Gates said that Syria is not immune to the revolutionary pressures building across the Arab world.

“What the Syrian government is confronting is in fact the same challenge that faces so many governments across the region, and that is the unmet political and economic grievances of their people,” he said at a news conference.

Gates, who met earlier Thursday in Cairo with Egypt’s military ruler, Mohammed Hussein Tantawi, held up that country as a model for allowing demonstrations to unfold peacefully. “The Syrians might take a lesson from that,” he said.

On Tuesday, rumors spread of a protest in Damascus. As tourists strolled through an outdoor bazaar in the old city near the historic Umayyad Mosque, more than a dozen police cars, a military truck loaded with soldiers and security trucks emblazoned with Assad’s picture were parked nearby.

The protest never materialized. The previous Friday, security officials had locked worshipers inside the mosque just as they began to chant prayers, preventing a planned demonstration.

Abd el-Karim Rihawi, of the Syrian Human Rights League, said most Syrians sympathize with Assad and would prefer him to be the agent of change.

“They don’t want to destroy their country,” Rihawi said. But, he added, referring to the government, “if they insist on dealing with this movement with an iron fist, I think maybe the situation will blow up — and we can’t imagine what that will look like.”

A special correspondent in Damascus, who cannot be named for security reasons, and staff writer Craig Whitlock, traveling with Gates, contributed to this report.