BEIRUT: A car bomb exploded Sunday in a government-held area outside the Syrian capital, killing at least five people and wounding 15, state media said.

The car bomb was detonated outside Sasa, southwest of Damascus. The Britain-based Syrian Observatory for Human Rights, an opposition-run monitoring group, said the explosion near a government checkpoint killed four, including three members of military intelligence. The state news agency didn't identify those killed, but said the wounded included women and children.

The al-Qaida-linked Fatah al-Sham Front claimed the attack, saying a gunman opened fire on the checkpoint before a suicide bomber struck.

Fighting has raged in opposition-held areas near Damascus despite a Dec. 30 nationwide cease-fire, including in the Barada Valley region, the primary source of water for the capital. A local truce there collapsed Sunday as the Lebanese militant group Hezbollah, an ally of the government, announced a resumption of military operations after a 24-hour pause.

The fighting has severely restricted the flow of water to the 4 million residents of Damascus, which has been without a reliable supply of tap water for more than two weeks.

Opposition activists say the truce failed because the government is asking the opposition to give up control of the entire valley.

The Observatory and another opposition group, the Wadi Barada Media Center, reported at least 13 airstrikes Sunday on villages in the valley. There was no immediate word on casualties.