The central Syrian city has become a center of resistance in the four-month-old uprising and poses a potential dilemma for Assad’s government. A major offensive could make the city a fresh rallying cry for the opposition, but Assad’s regime also does not want a repeat of last Friday’s stunning rally of an estimated 300,000 protesters.

Some of those fleeing Hama, who mostly live on the edge of the city, headed westward to the town of Salamiyeh about 30 kilometersaway, said Rami Abdul-Rahman of the Syrian Observatory for Human Rights.

“They are afraid of military operations in the area,” said Abdul-Rahman. Security forces have been conducting arrest raids on Hama’s outskirts for the past two days.

Details could not be independently confirmed. Syria has barred most foreign media from the country.

Hama holds an important place in the revolt against the rule of the Assad family. In 1982, the late Hafez Assad ordered troops to crush a rebellion by Islamist forces, killing between 10,000 and 25,000 people, rights activists say.

Security forces withdrew from Hama last month after a fierce crackdown on demonstrators that killed some 65 people — apparently hoping to appease angry, grieving families. But anti-Assad protests swelled. The outpouring last week was the largest protest since the mutiny against Assad’s regime began.

Defiant residents also have shuttered shops and set up road blocks throughout the city, said Abdul-Rahman and a Hama-based activist, hoping to prevent Syrian army troops from entering deep into the city.

The activist said young men kept watch on the streets and rooftops — hollering and calling out “God is Great!” as a warning sign when they suspected security officials were trying to sneak into the city.

“It’s like Tarzan, they call out like Tarzan,” said the Hama-based activist, who spoke on condition of anonymity because of fear of reprisals.

Some tanks withdrew from an entrance to the city on Thursday, but activists say there were no clear signals on the government strategy. Still, residents were nervous about a repeat of the 1982 assault, Abdul-Rahman said.

“I don’t think Syrian forces would do anything so stupid — because of the symbolism of Hama and the massacre,” Abdul-Rahman said. “Still, there’s nothing that can be ruled out.”