A man walks inside a mosque damaged by, according to activists, a barrel bomb thrown by forces loyal to Syria's president Bashar Al-Assad in Old Aleppo, May 1, 2014.
Syrian opposition activists say government aircraft struck a busy market in the rebel-controlled district of Aleppo, killing at least 33 people.
The Britain-based Syrian Observatory for Human Rights said Thursday's attack occurred in the Hillok area.
The attack comes a day after a strike on an Aleppo school left 18 dead, many of them children.
Aleppo has been divided between government forces and rebels, with forces loyal to Syrian President Bashar al-Assad carrying out frequent airstrikes and dropping crude barrel bombs in rebel-held areas.
Images from Syria
1/8A woman and a girl react after, according to activists, two barrel bombs were thrown by forces loyal to President Bashar Al-Assad, in Hullok neighborhood, Aleppo, May 1, 2014.
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2/8People inspect a site hit by what activists said were barrel bombs dropped by forces loyal to President Bashar al-Assad, in al-Letmana village, Hama province, May 1, 2014.
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3/8Men inspect a damaged room at a site hit by what activists said were barrel bombs dropped by forces loyal to President Bashar al-Assad, in al-Letmana village, Hama province, May 1, 2014.
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4/8People inspect a site hit by what activists said were barrel bombs dropped by forces loyal to President Bashar al-Assad, in al-Letmana village, Hama province, May 1, 2014.
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5/8Residents run after activists said two barrel bombs were thrown by forces loyal to President Bashar Al-Assad in Aleppo, May 1, 2014.
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6/8Injured children cry after activists said two barrel bombs were thrown by forces loyal to President Bashar Al-Assad in Aleppo, May 1, 2014.
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7/8Residents look for survivors through rubble after what activists described as a barrel bomb attack by forces loyal to President Bashar Al-Assad in Aleppo, May 1, 2014.
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8/8A man walks inside a mosque damaged by what activists described as a barrel bomb attack by forces loyal to President Bashar Al-Assad in Aleppo, May 1, 2014.
