Mortar attacks and air raids in two major cities in Syria killed at least 17 people, activists and government officials said on Tuesday, as a Kurdish opposition leader was killed in the north.

The deadliest attack struck the central city of Homs, which has been an opposition stronghold since the beginning of the two-year conflict and is now the target of a withering offensive by President Bashar Assad’s forces.

Three mortars slammed into a government-held district of Dablan before dawn on Tuesday, killing 10 people and wounding 26 others, a government official said.

He said many living in the neighborhood fled there to escape fighting elsewhere in Homs. The official spoke on condition of anonymity in line with regulations for civil servants.

The Britain—based Syrian Observatory for Human Rights said 11 people including a child were killed. The Observatory, citing hospital officials, also said attack happened late on Monday close to midnight.

In northern Syria, regime warplanes hit the town of Andan, killing seven people, including five children, the Observatory said.

Much territory in the north and the northeast along the borders with Turkey and Iraq has been under rebel control since last summer, when the opposition forces seized large swaths of land and several neighborhoods in Aleppo, Syria’s largest city. In February, rebels also captured Raqqa, the first city to fall entirely under opposition control.

In the past months, Assad’s troops regrouped and have been battling rebels on multiple fronts, capturing strategic towns near the border with Lebanon and steadily regaining control of territory they previously lost to the opposition, including around the capital, Damascus, the seat of Assad’s power. The battlefield successes largely have been credited to the regime’s superior firepower, including heavy artillery and fighter jets, as well as battle—hardened fighters from Lebanon’s militant Hezbollah group that have been fighting rebels alongside Syrian troops in recent weeks.

While the rebels have been forced into retreat on the central front, rebel—on—rebel fighting also has sapped energy from anti-Assad forces.

A prominent Kurdish opposition leader, Issa Hisso, was killed on Tuesday in a bomb attack in the city of Qamishli, near the border with Turkey, the Observatory said. There was no immediate claim of responsibility for the attack. A Kurdish member of the Syrian parliament, Omar Ossi, confirmed to The Associated Press that Hisso had died in car bombing.

Kurds, the largest ethnic minority in Syria, make up more than 10 percent of the country’s 23 million people. Their loyalties in the conflict are split. Kurdish rebel factions have fought al-Qaida lined militants in recent weeks for control of the territory they captured from the regime together.

More than 100,000 people have been killed in the conflict and millions have been driven out of their homes, seeking shelter in safer areas of the country or in the neighboring Iraq, Jordan, Lebanon and Turkey.

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