At least 24 people, including eight children, were killed when explosive barrels dropped by regime helicopters in the northern Syrian provinces of Idlib, Hama and Aleppo, the Syrian Observatory for Human Rights (SOHR) reported on Wednesday.Airstrikes killed at least 16 people, including eight children, in Tell Rifaat, north of the city of Aleppo, the London-based NGO said.The SOHR explained that the toll could increase, as searches continued and many of the wounded were in serious condition, Efe news agency reported.At the same time the NGO reported that at least eight more people were killed, including five female members of the same family, in similar barrel bombings early Wednesday morning in the northern provinces of Hama and Idlib, and that the toll there could increase as well.