Syrian forces overran the Baba Amr district of Homs on Thursday after rebels retreated, AFP reported.
As Free Syrian Army fighters pulled back, the opposition Syrian National Council (SNC) warned of a "massacre" in the neighbourhood by Syrian forces, while aid agencies said they would try to deliver aid and evacuate the wounded as early as Friday.
According to Col. Riyad al-Asaad of the Free Syrian Army, the army deserters had pulled out "tactically" from Baba Amr after nearly two days of an all-out assault by the Fourth Armoured Division, led by a younger brother of President Bashar Assad, Maher, following 27 straight days of shelling.
The Syrian Observatory for Human Rights said 21 people were killed in Homs on Thursday, including 17 civilians caught up in the battle for control of Baba Amr.
In total, 39 people, including eight Syrian army loyalists and seven deserters, were killed in violence across Syria on Thursday, the Observatory said.