Fighting in Syria's largest city, Aleppo, rages on after two weeks of clashes, with activists reporting that rebels used a tank to fire on a military airport.

The Britain-based Syrian Observatory for Human Rights says government forces shelled an Aleppo neighborhood Thursday, killing seven civilians.

Activists also say security forces launched a raid Wednesday in the Damascus are that killed dozens of people. Syrian state media said the operation targeted terrorists in the city.

Meanwhile, the United Nations said Thursday nearly 3 million people in Syria are in need of food assistance, and further warned that half of those need “urgent and immediate” aid in the next three to six months.

The U.N. Food and Agriculture Organization issued a statement along with the World Food Program saying the 17-month crisis in Syria has cost the country's agricultural sector $1.8 billion. But it said the humanitarian impact is far more important.

The findings are based on a joint assessment by the U.N. and the Syrian government.