Syrian civilians who flee areas controlled by the "Islamic State of Iraq and Syria" (ISIS) face mistreatment and death if they remain in areas under the group's control, but face the same dangers if they try to flee, a Syrian activist said.

Two women and a child died of dehydration this week as they attempted to flee the Deir Ezzor city of al-Mayadeen for al-Hasakeh city in searing temperatures, Deir Ezzor Under Fire activist Mahmoud Nader using a pseudonym to protect his identity told Diyaruna.

The three -- named as Zahra al-Sayel (Umm Naji), Ghsoun Mohammed Aref al-Alusi and her 3-year-old daughter Yamama -- were part of a convoy of 20 people, some of whom were in serious medical condition when they arrived.

"The convoy had endured temperatures of up to 50 degrees Celsius during their journey," Nader said, adding that the survivors are now receiving treatment.

Elsewhere in the province, ISIS elements on Wednesday (July 19th) rounded up 50 families from the town of Maadan in rural Deir Ezzor, Nader said.

"ISIS accused the families of attempting to leave the land of the caliphate and forced them to stay in the city of Deir Ezzor," he said.

"The real reason for the mass detention was to turn the civilians into human shields," he said, adding that the heavy presence of civilians will protect ISIS from airstrikes.

Meanwhile, on the pretext of investigating escapees from ISIS-controlled areas, some factions in northern Syria -- Faylaq al-Sham and al-Jabha al-Shamiya in particular -- have been mistreating and humiliating civilians, Nader said.

They have been stealing their personal possessions and any gold or cash they may have, he said, "although some are allowed to pass after paying a bribe or through prior arrangement with smugglers, who are active in the region".

Caught between two fires

"Deir Ezzor residents are fleeing in large numbers and are desperate to escape the area despite the dangers they may encounter," Nader said.

They face an intractable situation, he said.

If they stay where they are, "they face the cruelty of ISIS, insanely high prices and the threat of being detained and transported to the battlefronts", he said.

"They also are vulnerable to airstrikes targeting ISIS positions, as ISIS elements have spread out in all streets and homes to hide themselves among civilians," he added.

Reprisals for perceived "collaboration" with coalition forces can be harsh.

On Wednesday, ISIS charged Mohammed Satam al-Hameed with "apostacy" and executed him in a public square in the town of al-Quriya in rural Deir Ezzor.

The charge usually means the accused is opposed to the group and is co-operating with international coalition forces, Nader said.

ISIS also executed three pro-regime fighters in front of residents of Albu Kamal, he added, and its patrols have informed residents in some areas, especially areas near water tanks, that they must permanently evacuate those areas.

ISIS has been destroying water tanks and high walls around schools, houses and factories so that they cannot be used for protection by attacking forces when the battle reaches Deir Ezzor.