Syrian troops and tanks swept into the northern coastal town of Baniyas on Saturday to suppress anti-government demonstrations, tightening the squeeze on a persistent yet largely leaderless opposition movement that has refused to stop staging protests despite a deadly military crackdown.

Human rights groups said three women were shot dead in a village outside Baniyas when they joined a demonstration to protest the army’s actions, but that otherwise land lines and cellphone services to the town were cut off and no information was emerging about what was happening there.

At least 25 tanks rolled into the town about 2 a.m., according to rights groups and a witness who said soldiers were shooting into the air as they advanced through the darkened streets. The witness spoke by telephone before communications were cut, on the condition of anonymity because he feared for his safety.

Residents later formed a human chain to try to keep the soldiers away, according to Wissam Tarif of the rights group Insan.

Baniyas, which has emerged as a key protest town, was surrounded by the military and effectively placed under siege a month ago. Soldiers refused to allow supplies in and detained people who tried to leave, but otherwise they had made no attempt in the past two weeks to enter or to prevent the daily demonstrations in the town, according to residents contacted before Saturday’s clampdown.

The push into Baniyas, on the northern Mediterranean coast, appeared to replicate a similar assault launched nearly two weeks ago in the far southern city of Daraa, where the protest movement started, signaling that President Bashar al-Assad’s goverrnment remains intent on crushing by force the uprising that has erupted in recent weeks in almost every corner of the country.

Yet Syrians have continued to respond to activists’ calls for weekly protests after Friday prayers. This past Friday, tens of thousands of people turned out nationwide. On Saturday, Tarif said that the number of protesters killed by security forces the day before had climbed to 40, 17 of them in the city of Homs, north of Damascus.

Tarif said activists in Homs had told him that at least nine soldiers defected Friday, and Syrian state television has reported that 11 members of the security forces were killed in Homs on Friday.

But Saturday, communications were cut to Homs, as well as to the Damascus suburb of Zabadani, making it impossible to establish what was happening in those locations and suggesting that the government was also escalating its clampdown against opponents there, Tarif said.

Baniyas is significant also because it lies on one of the sectarian fault lines that government officials have warned could erupt in conflict if the protests are allowed to get out of hand. Baniyas is predominantly Sunni, but the surrounding villages are populated by members of the minority Alawite sect to which Assad and most senior government officials belong.

Assad’s government has sought to portray the uprising as led by armed Sunni Islamist extremists. But the Baniyas resident, speaking before the clampdown, said that the protesters are neither armed nor Islamist and merely want to express their frustrations with 48 years of Baath Party rule. “Sunnis, Alawites, Christians and Kurds are all protesting together,” he said.

At the protest in Baniyas on Friday, amateur video footage and photographs released by activists showed the demonstrators holding aloft red and white roses to signify their peaceful intentions.

The resident alleged, however, that the government has been distributing weapons to some residents of the adjoining Alawite villages, who have formed armed gangs, known as “shabiha,” or ghosts, to terrorize other residents. The potential for violence was illustrated last month by the unexplained shooting on the outskirts of Baniyas of nine soldiers, who may have been ambushed or may have been killed by their superiors for refusing to fire on protesters, according to conflicting news reports.