(CNN) -- Syrian warplanes struck Aleppo on Saturday, killing at least 40 people in a series of strikes in the city and province, the Syrian Observatory for Human Rights said in statement.
The rebel group said one of the strikes appeared to have been intended to hit a rebel headquarters, but it hit market stalls in the rebel-controlled Dawwar al-Hilwaniya neighborhood of the city. All of the victims, which included tens of wounded, were civilians, it said.
A second strike on the Karm al-Beik neighborhood of Aleppo killed seven, it said.
And 19 civilians -- including two children, a woman and four people who had not been identified -- were killed and dozens more wounded in a bombardment some 29 miles (46.5 km) northeast of Aleppo near Tareeq Al-Bab and the adjoining town of Tadif, it said.
Opposition activists posted footage on YouTube showing what they said was the aftermath of the airstrike in Aleppo. Dozens of people were clambering over the wreckage of buildings. Another YouTube posting showed a plume of smoke -- from an apparent explosion -- rising into the air.
CNN cannot verify the authenticity of the videos.
In a separate incident, Islamist rebels captured a major oil field in the Deir Ezzor province, in eastern Syria, the Observatory said Saturday in a statement. The rebels included members of Jabhat al-Nusra, an al Qaeda affiliate, the London-based opposition group said.
The rebels were in full control of the al-Omer oil field following clashes that started Friday night, it added. With the loss of the oil field, the Syrian government has lost control over all oil fields in the eastern part of the country, the statement said.
The official Syrian Arab News Agency, which did not cite either incident, reported Saturday that the army had "resumed its national duty in hunting the armed terrorist groups in different Syrian cities, killing many terrorists and storming hideouts of several others."
The government typically refers to rebels as terrorists.
The Syrian conflict began in March 2011 after government forces cracked down on peaceful protesters during the Arab Spring movement and is now a full-blown civil war. The United Nations estimates that more than 100,000 people have died in the conflict.