A blast rocked the northern Syrian city of Aleppo on Sunday killing 17 people and wounding 40, the official Syrian state news agency reported.
The agency said the explosion occurred near a hospital and a school, which residents said was being used to house soldiers fighting an uprising against President Bashar al-Assad.
Earlier on Sunday, airplanes bombed residential districts of the city, killing and wounding dozens of people, opposition activists said.
They said the air raid destroyed a residential building in the Hananu neighborhood, one of several in eastern Aleppo under insurgent control. The death toll was not immediately clear but bodies and wounded people were being dug out from the rubble.
Video footage from the area, taken by activists in the almost 18-month-old uprising against President Bashar al-Assad, showed scores of people searching and digging in the rubble of a flattened building.
Several houses were destroyed in the shelling of the northern city’s Midan district, which is under regime control, said the Syrian Observatory for Human Rights.
Fierce battles broke out on the edge of Midan on Saturday, after rebels tried to take over the district from their stronghold in Bustan al-Basha.
A main water pipe in Bustan al-Basha was destroyed, either by air strikes or the fighting, and water shortages were reported by residents in Aleppo.
In the eastern city of Deir Ezzor, the army shelled the neighborhood of Jubaila, while two people were killed at a checkpoint in Hamdaniyeh district and a third was shot dead by a sniper in Jura.
Shelling attacks were also reported in the northwestern province of Idlib and in the southern province of Daraa, but there were no reports of casualties thus far, the Observatory said.
The violence followed a bloody day in which as many as 172 people have been killed by the fire of Syrian forces across the country on Saturday, including 89 in Aleppo, Al Arabiya reported citing activists at the Local Coordination Committees.