Syrian troops opened fire on people throwing stones to stop a military convoy from advancing toward the eastern city of Deir el-Zour, killing as many as three people Saturday, activists said, as government forces intensified a pre-Ramadan crackdown on protesters calling for President Bashar al-Assad’s ouster.

Activists have predicted that demonstrations will escalate during the Islamic holy month, which begins Monday, as both sides try to tip the balance in the months-long uprising.

During Ramadan, Muslims throng mosques for special night prayers after breaking their daily dawn-to-dusk fast. Such gatherings could trigger protests throughout the predominantly Sunni country, and activists say authorities are moving to ensure that does not happen.

Syria-based rights activist Mustafa Osso said authorities have detained more than 4,000 people in raids over the past week as they try to contain the situation.

“The regime is trying to suppress the uprising because it knows that the opposition will try to hold protests between sunset and sunrise,” Osso said.

On Saturday, government forces stormed parts of Deir el-Zour and barraged neighborhoods with heavy machine-gun fire, two days after army defectors fought with Assad loyalists, activists said.

An activist in Deir el-Zour said the attack began in the afternoon and that one person was shot dead in a nearby village. Rami Abdul-Rahman, the director of the London-based Syrian Observatory for Human Rights, gave a higher death toll, saying troops shot dead three people in the nearby village of Tibni when they tried to stop advancing troops by throwing stones.

Deir el-Zour, the capital of a province that carries the same name, is an oil hub but one of the country’s poorest regions. The tribal region, which borders Iraq, has been the scene of intense anti-government protests.

The Deir el-Zour raid followed a nighttime attack by government forces on the capital, Damascus, and the eastern city of al-Boukamal, on the border with Iraq.

The Syrian Observatory said four people were killed during a raid on the Damascus suburb of Kiswah on Friday night. It also said that one person was killed when troops entered al-Boukamal. Those deaths raised the total death toll on Friday to 12, according to the human rights group.

Mohammed Abdullah, a spokesman for the Local Coordination Committees, which track the protests in Syria, said at least six people were killed in the Kiswah raid, and he gave a total death toll of 22 for Friday.

Ammar Qurabi, who heads the National Organization for Human Rights in Syria, said 19 people were killed Friday, including three in Kiswah and two in al-Boukamal.

— Associated Press