(Reuters) – Syrian army helicopters killed at least 20 people, mostly children and women, in the first attack on a refugee camp in southern Syria along the border with Jordan, residents and opposition activists said. They said the army dropped several barrel bombs – highly destructive improvised explosives, use of which has been condemned by Western powers as a war crime – on the camp in the village of Shajra, 2 km (1 mile) from the Jordanian border.