Airstrikes killed 58 people in northwestern Syria on Saturday, hours after the US and Russia announced a new ceasefire plan, a rights group said.
The attack targeted a market in the rebel-held city of Idlib, according to the monitoring group Syrian Observatory for Human Rights.
Thirteen children and 13 women were among those killed as people shopped during the holiday Eid al-Adha. Tens of others were wounded.
The death toll is expected to rise, according to the monitoring group.
The ceasefire plan, announced Friday, calls for the Syrian government and the opposition to respect a nationwide ceasefire. It is scheduled to go into effect at sundown Monday.
The Syrian regime announced its support of the ceasefire deal Saturday, according to the state-run TV.
U.S. Secretary of State John Kerry said the accord would prevent President Bashar al-Assad’s air force from flying combat missions anywhere the opposition is present, calling this provision the “bedrock of the agreement.” He labeled the Syrian air force the “main driver of civilian casualties” and migrant flows.
In February, a cessation of hostilities negotiated between Kerry and Russian Foreign Minister Sergey Lavrov fell apart within weeks, and efforts to reach a political settlement in the war-torn country have been on the verge of collapse.