At least 17 people have been killed by a car bomb in Syria’s largest city, Aleppo, state news agency Sana says.
Syrian state TV said two hospitals and a school were largely destroyed by the blast near the city sports stadium.
The Free Syrian Army said it carried out the attack because the facilities were being used by government troops. Earlier, a strike killed at least five people, witnesses said.
It comes as the new UN-Arab League envoy begins a mission to the region.
Lakhdar Brahimi, who last month replaced Kofi Annan as special envoy to Syria, will hold talks with Arab League and Egyptian officials ahead of meetings in Damascus.
When he took over the post, Mr Brahimi said bringing peace to Syria would be “nearly impossible”.
As violence continued, activists said more than 100 people were killed across Syria on Sunday.
In Aleppo, where government troops are trying to flush out rebels, state TV showed damaged buildings and rescue workers pulling survivors from the rubble after the car bomb went off.
Reuters news agency quoted an activist, Ahmad Saeed, as saying the army had previously taken over the neighbourhood and turned the hospital into a barracks.
The attack came shortly after warplanes dropped bombs on rebel targets in the east of the city, with reports of at least five people killed.
Reports from Syria are almost impossible to verify because of severe restrictions on foreign journalists in the country.
The UN says more than 18,000 people have been killed since the conflict began in March 2011. Activists put the death toll at 23,000.
Mr Brahimi’s visit comes amid an impasse in efforts to find a diplomatic solution to the fighting.
On Sunday, US Secretary of State Hillary Clinton dismissed a Russian proposal for a new UN Security Council resolution on Syria as pointless “with no teeth”.
Russia says it wants Security Council approval for a peace plan agreed in June in Geneva that called for a ceasefire and political transition.
But Mrs Clinton said a resolution without consequences would be ignored by Syrian President Bashar al-Assad.
BBC