At least 17 people have been killed and dozens wounded in the Syrian province of Sweida in clashes between armed residents and gangs aligned with state security agencies, activists and local media said on Thursday.

The Druze-majority province has remained mostly shielded from the bloody conflict that ravaged the rest of the country since 2011 but sporadic rallies have taken place over deteriorating economic conditions. The Syrian government exerts less military and administrative control of the region than other government-held areas.

Residents have been growing increasingly frustrated at government-backed fighters carrying out arbitrary detentions, random roadblocks and kidnappings for ransom, said Rayan Maarouf, an activist and head of the Suwayda24 local media outlet.

At the weekend, the detention of one resident prompted others to set up informal roadblocks and detain members of government-backed gangs and besiege their bases, Suwayda24 reported.

"This uprising flared up very suddenly and there were attacks on the bases of these armed groups, which are reinforced with heavy weapons," Maarouf told Reuters late Wednesday.

One resident of Atil, one of the villages swallowed up by fighting, said the clashes were so heavy he was unable to leave his house to get urgent medical supplies for his sister.

"It was 15 hours of full-on war. The cars, the solar panels, the water tanks - they all got destroyed," said the resident, who preferred to use his first name Shadi.

The resulting fighting left 17 people dead according to Sweida's health directorate, which was cited by both Suwayda24 and the pro-government Al-Watan newspaper on Thursday.

Most of the dead were members of the state-aligned gangs and muted funerals were held for them on Thursday, Maarouf told Reuters.

The rest, from a movement linked to Druze religious figures and known as the "Men of Dignity," were mourned in two processions that drew in around 2,000 people each, he added.

The Syrian government has not commented on the violence but Al-Watan said the fighting had quietened and negotiations over a settlement were underway.

The man kidnapped at the weekend was ultimately released, Sweida24 reported.

Sweida had seen rare protests earlier this year, when dozens gathered in the provincial capital to demand a halt to cuts in gas subsidies.

(Editing by Philippa Fletcher)