Seventy-six people, including 28 children, were killed on Sunday when Syrian army helicopters dropped "barrel bombs" on the northern city of Aleppo, the Syrian Observatory for Human Rights has said.  Barrel bombs are explosive-filled cylinders or oil barrels, often rolled out of the back of helicopters with little attempt at striking a particular target but capable of causing widespread casualties and significant damage.  Another activist group, the Local Co-ordination Committees, put the death toll at 83. It said that number was likely to rise because of the large number of wounded and the lack of sufficient medical supplies.  The Britain-based Observatory said Syrian government aircraft were conducting a new round of air strikes on Monday in the southern province of Daraa, including the villages of Inkhil and Jassem. It also reported new air raids on Aleppo, and said rebel groups had issued a statement asking civilians in government-held parts of the city to move away from state security buildings, which they said would be targeted in retaliation for the bombings.  President Bashar al-Assad's forces, battling rebels in a two-and-a-half-year conflict that has killed more than 100,000 people, frequently deploy air power and artillery against rebel-held districts across the country.  They have been unable to recapture eastern and central parts of Aleppo, which rebels stormed in the summer of 2012, but they have driven rebel fighters back from towns to the south-east of the city in recent weeks.  The conflict has grown sectarian, with majority Sunni rebels battling Assad's own Alawite sect and Shia militia.  The Observatory – which has a network of opposition, pro-government and medical sources – also said on Monday that rebels in northern Aleppo province were threatening to strike two Shia villages they have surrounded with missiles if barrel bombs were used again by the army.
Human rights group says rebels have warned civilians to stay away from government buildings as they plan retaliation