BEIRUT – A Syrian missile strike leveled a block of buildings in an impoverished district of Aleppo on Tuesday, killing at least 33 people, almost half of them children, anti-regime activists said.

Many were trapped under the rubble of destroyed houses and piles of concrete and the death toll still could rise further if more bodies are uncovered.

The apparent ground-to-ground missile attack struck a quiet area that has been held by anti-regime fighters for many months, a reminder of how difficult it is for the opposition to defend territory in the face of the regime’s far superior weaponry.