IDLIB - Unidentified assailants shot dead seven members of Syria's White Helmets rescue service early Saturday during a raid on their base in a jihadist-held northwestern town, the group said.
The attackers struck in the town of Sarmin, nine kilometres (six miles) east of the city of Idlib, that is controlled by the Hayat Tahrir al-Sham jihadist alliance.
"The civil defence centre in Sarmin was the target of an armed attack by unknown assailants in which seven volunteers were killed," the White Helmets said in statement.
"Two minibuses, some white helmets and walkie-talkies were stolen."
It was not immediately clear whether the motives for the raid were political or purely criminal.
The Syrian Observatory for Human Rights said the seven volunteers had all been killed by bullets to the head.
"Colleagues came in the morning for the change of shift and found them dead," its director, Rami Abdel Rahman, said.
The White Helmets emerged in 2013, working to rescue civilians in rebel-held areas.
They have since gained international renown for their daring rescues, often filmed and circulated on social media, and were nominated for the 2016 Nobel Peace Prize.
Although they work exclusively in rebel-held areas, they insist they are non-partisan.
Their detractors, including President Bashar al-Assad's government and his ally Russia, accuse them of being tools of their international donors.
They receive funding from a number of Western governments, including Britain, Germany, the Netherlands and the United States.
Critics also accuse them of harbouring rebel fighters, including jihadists, in their ranks.
- Attack near Jordan border -
At least 23 rebel fighters were killed Friday and dozens more wounded in a suicide blast in southern Syria near the border with Jordan, a monitoring group said.
The Syrian Observatory for Human Rights said the bomber detonated an explosive belt at a base used by Jaish al-Islam (Army of Islam) near the Nasib border crossing.
"Most of the 23 rebels killed were from Jaish al-Islam. Dozens were wounded, including 20 in critical condition," said Observatory head Rami Abdel Rahman.
There was no immediate claim of responsibility, but jihadists linked to the Islamic State group have attacked rebels in southern Syria.
The Nasib border crossing -- known as Jaber on the Jordanian side -- lies in Syria's southern Daraa province and was captured by rebel groups in April 2015.
Syria's uprising erupted in Daraa province in March 2011 with widespread protests calling for the ouster of President Bashar al-Assad.
It has since turned into an all-out war that has drawn in international powers and killed more than 330,000 people.
Under a plan hammered out in May between Russia, Turkey and Iran at peace talks in Kazakhstan, four "de-escalation zones" were to be established across swathes of Syria to ease fighting between regime and rebel forces.
Parts of southern Syria make up one zone. Another lies in the rebel bastion of Eastern Ghouta near Damascus, while a third is in the central province of Homs.
The fourth zone, in northwestern Idlib province, has yet to be implemented.