At least 16 people have been killed in the central Syrian city of Hama as government forces intensify their operations in the city, human rights activists have told Al Jazeera.
Sumer al-Said, a resident of Hama, told Al Jazeera by phone on Tuesday afternoon that security forces had shot people indiscriminately in the streets, and that water and electricity had been cut off.
"Two days ago, they arrested a lot of people in my area, and a lot of people were badly beaten," he said.
In-depth coverage of escalating violence across Syria
Troops and tanks have surrounded the city in recent days in an apparent attempt to quell protests against the rule of President Bashar al-Assad.
With tanks and armoured vehicles moving closer to the edges of the city in the early hours of Tuesday, residents said hundreds of youths had blocked roads leading to residential neighbourhoods with garbage containers, wood and metal to try to prevent a possible advance.
Al Jazeera's Rula Amin reported that by Tuesday evening, security forces had broken through many of the roadblocks that locals have been erecting.
Security forces, some in plain clothes and some in uniform, have set up checkpoints across the city, making arrests and preventing people from fleeing, she said.
Syria has banned most international media from operating in Syria, making it difficult to verify reports from activists and authorities.
Anas al-Abdeh, a member of the Damascus Declaration Abroad opposition movement, told Al Jazeera from Manchester that his sources within the city told him armed men were carrying out "cleansing" operations against the city's inhabitants, moving from one area to the next.
"They told me that there are many Shabiha, which is the militia supporting the Syrian regime, backed by Syrian security forces, massing across the city," he told Al Jazeera. "The people are very afraid."
"Someone called Khaled was killed this morning ... there is a state of war in Hama and we don't know the future," he said.
Hama, the scene of a bloody crackdown by Assad's father nearly 30 years ago in which as many as 20,000 people died, has witnessed some of the biggest demonstrations in Syria's latest uprising against one-party rule, inspired by revolts across the Arab world.
"Hama carries a very significant symbolism," Amin reported. "What's happening now is bringing back these memories.
Tens of thousands gathered in the central city square last Friday, calling on Assad to step down. Some local members of the Baath Party have defected in recent days, Said told Al Jazeera.
Assad sacked the governor the following day and deployed troops and tanks to the city.
Residents said at least three people - including a 13-year-old boy - were killed in the assault. The tanks pulled out of the city after the operation, only to return to the city's edges on Monday.
Hundreds have died nationwide since Assad ordered his forces to stamp out the protests against his rule.
In recent days, government troops have attacked villages and towns in the Jabal-al-Zawya region, north of Hama.
The Syrian Observatory for Human Rights said tanks stormed the town of Kfar Nubbul early on Tuesday "without meeting a single shot in the town that has seen peaceful protests since the beginning of the uprising".
"What's happening now is bringing back these memories."
Al Jazeera's Rula Amin
There was speculation though over whether troops and tanks would re-enter Hama.
"Assad may wait to see whether large-scale protests in Hama continue. He knows that using military aggression against peaceful demonstrations in a symbolic place like Hama would lose him support even from Russia and China," Mohammad Abdallah, another Syrian activist, told Reuters from exile in Washington.
Both the Kremlin and Beijing have opposed a United Nations Security Council resolution proposed by the West against Damascus, helping Assad withstand mounting international isolation.
Abdallah said using tanks to attack Hama would also "totally discredit" promises by Assad for a national dialogue with the opposition to discuss political reforms in Syria.