"Mosques are calling for blood (donations) for 14 people badly wounded," one resident, a computer programmer who declined to be named, told Reuters by phone.
"Three tanks and four armoured personnel carriers have been deployed in and around the main square. Thousands of people still went out in a night demonstration," he added.
On Sunday Assad, from Syria's minority Alawite sect, replaced the civilian governor of Deir al-Zor province with a secret police officer, two days after the biggest pro-democracy demonstrations in the province so far in the uprising.
Last week the army surrounded the town of Albu Kamal on the easternmost edge of Deir al-Zor, which borders Iraq, after 30 soldiers defected following the killing of four protesters, residents said.
Deir al-Zor produces most of Syria's oil output of 380,000 barrels per day but is among the poorest of the country's 13 provinces.
In Madaya near the capital Damascus, residents told Reuters two civilians were killed in a security sweep. Madaya has witnessed large protests demanding the toppling of Assad, despite the stationing of armoured vehicles in the area.
Syrian authorities have expelled most independent journalists since the uprising erupted four months ago and do not usually comment on reports of killings.