Updated

Two Syrian activist groups say an airstrike in a rebel-held neighborhood in the northern city of Aleppo has killed at least 20 people, including children.

The Britain-based Syrian Observatory for Human Rights and the Aleppo Media Center say the bombing occurred in the city's Sukkari neighborhood on Monday.

Syria's military has been dropping crude barrel bombs over Aleppo's rebel-held areas. The Observatory, which relies on activists on the ground, says the airstrikes have killed nearly 2,000 since January.

Aleppo is Syria's largest city. It has been carved up into rebel- and government-controlled areas since opposition fighters launched an offensive in the north in mid-2012.