This week, hundreds of civilians escaped Raqa and headed north to the camp in Ain Issa, in territory controlled by the Syrian Democratic Forces, a US-backed Arab-Kurdish alliance.
As part of their campaign to capture Raqa, the Syrian heart of the jihadists' so-called "caliphate", the SDF have been bearing down on the IS-held Tabqa Dam over the past 10 days.
Rumours that Syria's biggest dam would collapse and flood Raqa, 55 kilometres downstream, have sparked panic in the city.
"The hisbah (religious police) announced over the megaphones 'the land of Muslims will be flooded, the Tabqa dam has collapsed,'" said Mohammad Mahmoud, 38.
Mahmoud, his brother and both their families paid $1,000 to a smuggler and fled Raqa on foot earlier this week.
"I was so afraid, I couldn't think straight," he said.
The camp where he has found shelter is home to several thousand Syrians displaced by war, including 400 families who arrived this week from Raqa.
Children waddled through makeshift pathways between tents emblazoned with the logo of the UN refugee agency (UNHCR), clutching sandwiches and water bottles.
Inside tents, men waited for their turn to have their IS-mandated beards shaved then examined their bare chins in a small mirror.
- 'It's hell there' -
Mahmoud's face was weighed down by exhaustion, his clothes covered in dust.
He hovered protectively around his elderly mother who sat in a wheelchair, its wheels caked in mud after their arduous 14-hour trek out of Raqa.
"It's hell there. Fear rules over everything," he said as he took apparent pleasure puffing on a cigarette, a vice which IS banned when they captured Raqa in 2014.
"IS is finished now. Most of its fighters fled to Mayadeen or Albu Kamal," two towns in the oil-rich eastern province of Deir Ezzor, most of which is under IS control.
At the entrance to the camp, Kurdish police units -- known as Asayesh -- searched visibly shaken new arrivals.
Ahmad, a Raqa native in his 50s, said residents seized the opportunity to flee when they saw IS fighters leave.
"We were no longer afraid to flee Raqa like before, because IS fighters were less and less visible," he said, his six children perched atop suitcases packed with their belongings.
Ahmad said the jihadists "abandoned most of the checkpoints, built tunnels around the city" and protected their positions with sand bags.
He said the journey to Ain Issa was traumatic.
"We were so terribly afraid of the air strikes, that the coalition might think we are IS fighters," he said.
- 'Daesh is afraid' -
"Daesh is afraid of the assault on Raqa," a 25-year-old man who asked to use the pseudonym of Zuhair for security reasons, said using an Arabic acronym for IS.
"Many of their fighters fled with their families on motorbikes and there are fewer and fewer checkpoints," he said.
But even as the jihadists left, "they warned residents 'not to go to the infidels,'" said Zuhair, who still has relatives trapped in Raqa, a city of 300,000 residents.
"I don't know what happened to them," he said, tearing up.
IS applies an ultra-conservative interpretation of Islamic law in territory under its control, torturing or executing law-breakers.
Zuhair said he was jailed and lashed by jihadists several times for selling tobacco in defiance of an IS ban.
"But if I hadn't taken the risk, I couldn't have fed my family," he said, crouched near his one-year-old daughter Qamar.
Syria's conflict began in 2011 with anti-government protests, but has since turned into a multi-front war that has killed more than 320,000 people and forced millions to flee their homes.
Since March 21, the battle for Tabqa Dam and the adjacent town has killed at least 110 civilians and 68 jihadists, according to the Britain-based Syrian Observatory for Human Rights.
It said SDF fighters were around two kilometres from Tabqa.
Jilal al-Ayyaf, who runs the camp in Ain Issa, said he was bracing for an influx of displaced people as the SDF press their advance.
"The more the noose tightens (around IS), the more displaced people we'll get," he said.