At least 18 people were killed on Monday when rebels fired improvised rockets at residential areas in Syria's northern city of Aleppo, a media report saidThe rockets slammed into the government-controlled districts of Serian and Faisal in Aleppo, Xinhua reported citing the state news agency SANA. Children were among those killed.The rockets were fired from the rebel-held Bani Zaid district in Aleppo, according to the report. Syria's Information Minister Omran al-Zoubi slammed the firing as an act of terrorism, which, he said, is supported by the Turkish government, which emerged as one of their main backers of the militant groups in Syria.Aleppo, Syria's second largest city and once an economic hub, has been carved out between the rebels and the government troops.Tens of civilians have been killed by similar rebel shelling during the crisis, while the rebels accuse the government troops of shelling rebel-held areas with crude barrel bombs that they claim has killed several civilians.