A war monitoring group says Islamic State of Iraq and Syria (ISIS) fighters seized 36 women and children during simultaneous attacks on the southeastern province of Sweida last week. The London-based Syrian Observatory for Human Rights said Monday that 20 women and 16 children were seized from al-Shobki village in Sweida during the Wednesday attacks.

The ambush by suspected ISIS militants left at least 221 people dead. Reports on social media suggest ISIS has sent photos of some of the kidnapped women, most of them from the minority Druze sect prevalent in Sweida, to their families in via WhatsApp.

The suspected ISIS kidnappers have purportedly made demands for the women and children's release, but the families have not said what they're demanding.

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Syrian warplanes carried out a number of airstrikes targeting ISIS positions in the northern and eastern countryside of Sweida at dawn on Monday. The strikes targeted the Kara'a area, which is considered a major ISIS stronghold in the desert of Sweida province.

Sweida, which is mainly government-held and populated with members of Syria's Druze minority, had been largely insulated from the conflict raging in the rest of the country since 2011, but on Wednesday, a string of suicide blasts and shootings claimed by ISIS shattered the peace in the provincial capital and nearby villages, most of them civilians.

The ISIS jihadists abducted the women and children from al-Shobki village, according to the Syrian Observatory, which said four women had since managed to escape while another two had died. That left 14 women and 16 children in ISIS captivity, said Observatory head Rami Abdel Rahman. Another 17 men were unaccounted for, but it was unclear if they were also kidnapped.

Damage is seen after a suicide bomb attack in Sweida, southern Syria, July 25, 2018. SANA/REUTERS

ISIS has not claimed the kidnappings and no details on them could be found on its propaganda channels. Local news outlet Sweida24 and other online outlets published a video that appeared to show one of the hostages making demands of the Syrian government, purportedly on ISIS' behalf.

The video's authenticity could not be independently verify, but several Sweida residents confirmed that a woman appearing in the video was among those missing after the attacks.

The hostages mainly hail from two large families in Al-Shobki, said reporter Nour Radwan, who heads Sweida24. The remote village lies in the eastern edges of Sweida province and suffered some of the deadliest violence from Wednesday's attacks, with more than 60 civilians killed in Al-Shobki alone, Radwan said.

"Most of its residents are farmers and don't have much more than hunting rifles in terms of weapons, so there was little resistance from Al-Shobki compared to other villages," he told AFP.

The jihadists are demanding the release by the Syrian government "of detained IS-linked people, whose numbers are now being negotiated", said Radwan, using an alternate acronym for ISIS.

The Sunni Muslim extremist group also wants a halt to a Syrian regime offensive on jihadist positions, he said. Religious leaders from the Druze community have since stepped in, Radwan and another local source with knowledge of the talks told AFP.

"As of Sunday, the hostages were still being held in the Badiya. Negotiations are happening between Daesh and Druze sheikhs," said the source, using the Arabic acronym for ISIS.

ISIS has lost urban strongholds in Syria but still holds parts of the sprawling expanse of desert know as the Badiya, including northeastern areas in Sweida and territory by the Iraqi border.

The jihadists also control a pocket in Daraa province, directly west of Sweida.

Backed by Russia, Syrian troops have been waging an assault on an ISIS-held pocket of Daraa for nearly two weeks.

On Monday, they began bombing operations ahead of an attack on the main ISIS-held town of Ash-Shajara in Daraa, Syrian state television said.

Since its bloody rise to power in 2014, ISIS has carried out multiple mass abductions in Syria and Iraq, including of minorities.

It kidnapped more than 220 Assyrian Christians in northeast Syria in 2015 and another 270 Christians from a central village the following year. Most of the hostages were released after negotiations.

Under the group's ultra-conservative interpretation of Islam, minorities are considered "infidels" but ISIS also politicises them as regime loyalists.

More than 350,000 people have been killed since Syria's conflict erupted in 2011.

Wednesday's violence was the worst Sweida had seen since the war began, and one of ISIS' deadliest attacks across the country.

ISIS attackers detonated suicide bombs in Sweida city and villages to the north and east, while others shot and stabbed residents. A total of 139 civilians were among more than 220 people killed, according to the Observatory. The remaining were pro-government fighters or residents who had picked up arms to defend their homes.