Syrian airstrikes targeting a stronghold of the Islamic State extremist group, including one that struck a crowded bakery, killed at least 13 civilians on Saturday, activists said.
The eight airstrikes targeted the northeastern city of Raqqa, which is under the full control of the militant group, said the Britain-based Syrian Observatory for Human Rights.
Most of the civilians were killed after at least one strike hit a bakery on a busy street, and the death toll was likely to rise, said the Observatory, which obtains its information from a network of activists on the ground.
The airstrikes were also reported by a Moscow-based activist who uses the name Abu Ibrahim and is a member of a media collective called "Raqqa is being silently slaughtered."
The local morgue was packed with charred bodies, making identification difficult, said Abu Ibrahim. He said the dead included at least eight members of one family.
Other strikes hit a government finance building that the Islamic State used as its headquarters and another building used as a jail, Abu Ibrahim said.
It has been virtually impossible for journalists to visit Raqqa since the town fell to the Islamic State group, which routinely abducts reporters and recently beheaded two American journalists in response to U.S. airstrikes against the militants in Iraq.
The strikes were part of an uptick of government military action against the Islamic State group since it swept into neighboring Iraq, seizing northern and western swaths of that country and declaring a proto-state straddling the border.
Syrian President Bashar Assad's government has also suffered heavy losses against the Islamic State group, which killed hundreds of soldiers and pro-government fighters in recent months as it overran oil fields and military bases. There was no immediate government comment on the airstrikes.