An air strike near a bakery in the rebel-held town of Halfaya in the central Syrian province of Hama on Sunday killed dozens of people, a monitoring group said.
"Dozens of people were killed in an air strike on Halfaya," said the Syrian Observatory for Human Rights, while activists in Hama said the raid had targeted a bakery in the town.
"In Halfaya, regime forces bombarded a bakery and committed a massacre that killed dozens of people, including women and children, and wounded many others," said the Local Coordination Committees, a grassroots network of activists.
"A MiG (jet) has attacked! Look at (President Bashar al-) Assad's weapons. Look, world, look at the Halfaya massacre," says an unidentified cameraman shooting an amateur video distributed by the Observatory.
The footage showed a bombed one-storey block, and a crater in the road beside it.
Bloodied bodies lay on the road, while others could be seen in the rubble.
Men carried victims out on their backs, among them at least one woman, the video showed.
On Monday, rebels launched an all-out assault on army positions across Hama, which is home to strong anti-regime sentiment.
During the summer, rights groups accused government forces of committing war crimes by dropping bombs and using artillery on or near several bakeries in the northern province of Aleppo.
One of the bloodiest attacks was on a bread line in the Qadi Askar district of Aleppo city on August 16 that left 60 people dead, according to local hospital records.