Shelling and air raids by Syrian government forces against a string of villages in the northwestern province of Idlib killed at least 29 people late on Sunday, a watchdog said.
The military carried out five separate strikes, including a rocket attack on the village of Maghara that killed 13 people, the Syrian Observatory for Human Rights said on Monday.
The attacks all came shortly before iftar, the meal at which Muslims break their daytime Ramadan fast, according to the Britain-based group, which relies on a network of activists, lawyers and doctors on the ground across Syria.
The attack in Maghara was the deadliest, but the Observatory also reported six killed in the village of Al-Bara, four in Basamis, three in Kfar Nabl in an air strike and three in Iblin.
The dead included at least eight women and six children, the Observatory said.
Video footage posted online by activists showed harrowing scenes of death and destruction, including fires started by what they said was the rocket strike on Maghara.
The screams of survivors were heard as the camera panned over the rubble.
"God is great. Where are our Muslim brothers? Where are our Arab brothers?" the activist says as he films residents trying to dig out people trapped beneath the wreckage of their homes.
"This is the iftar of the Muslims in Jabal Zawiya," he said, referring to the hill district where the village lies.
"A massacre in the village of Maghara."
A second video showed smoke billowing over the village and residents lifting a dust-covered older man, his stomach torn open, onto a flat-bed truck.
Another man lay dead on the ground, his body and clothes covered in grey dust flecked with blood, his mouth open, his arm curled upwards and his hand lying on his chest.
Residents scooped water into bowls and buckets to try to put out the fires.