Many people, among them children, were still trapped under the rubble, the sources said.
"16 of the people who were killed were from the same family," one medical source said.
The Britain-based Syrian Observatory for Human Rights said in the last 24 hours it documented at least 30 deaths in the city of al-Raqqa, including 14 children.
It added that the number is likely to increase as there are many wounded people still listed in critical conditions.
The UN estimates that up to 50,000 people are still trapped inside al-Raqqa city that has been under Islamic State control since 2014.
Meanwhile, airstrikes by unidentified planes on Tuesday hit al Mayadeen in Deir al-Zour,in eastern Syria, wounding at least 20 people among them little children, the Observatory said.
The US-led alliance has intensified its air campaign in and around al-Mayadeen city which the radical group has controlled since May.
The Islamic State has suffered military setbacks in recent months, losing ground in Syria and neighbouring Iraq.
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"16 of the people who were killed were from the same family," one medical source said.
The Britain-based Syrian Observatory for Human Rights said in the last 24 hours it documented at least 30 deaths in the city of al-Raqqa, including 14 children.
It added that the number is likely to increase as there are many wounded people still listed in critical conditions.
The UN estimates that up to 50,000 people are still trapped inside al-Raqqa city that has been under Islamic State control since 2014.
Meanwhile, airstrikes by unidentified planes on Tuesday hit al Mayadeen in Deir al-Zour,in eastern Syria, wounding at least 20 people among them little children, the Observatory said.
The US-led alliance has intensified its air campaign in and around al-Mayadeen city which the radical group has controlled since May.
The Islamic State has suffered military setbacks in recent months, losing ground in Syria and neighbouring Iraq.
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