(CNN)Syrian rebel groups launched a surprise attack on regime forces on the eastern outskirts of Damascus on Sunday, according to opposition groups, the Syrian Observatory for Human Rights and Syrian state media.
Clashes broke out in the Syrian capital, which has not seen such attacks in months, if not years, said SOHR Director Rami Abdel Rahman.
The rebel fighters began the attack from the district of Jobar in northeastern Damascus, an area split between rebel and government control. The rebel factions seem to have prepared for this offensive, Rahman said.
Since the start of the conflict, the Syrian regime and allied militias have held a very tight grip on the capital. The opposition only has a few pockets of control around Damascus, including a part of Jobar.
The assault was led by Islamist groups including Ahrar al-Sham and the recently formed umbrella Jihadist group Hayat Tahrir al-Sham that includes Jabhat Fatah al-Sham.
Syrian state media reported that Syrian forces had repelled an attack by jiahdist fighters, who also used tunnels to attack government positions.