Eastern Syria CNN  — 

Some 500 ISIS fighters surrendered to US-backed Syrian Democratic Forces on Tuesday, amid the final push to wrest the jihadist group from Baghouz, its last remaining enclave in eastern Syria.

The militants were among a wave of people fleeing fighting in the village, near the Iraqi border, which has been pummeled by US-led coalition airstrikes in recent weeks.

A CNN team was at a reception area on Tuesday where thousands were being processed – both militants and civilians. SDF spokesman Mustafa Bali said on Twitter that 3,500 people were evacuated from Baghouz on Tuesday alone.

Civilians evacuated from Baghouz wait at a screening area held by the US-backed Syrian Democratic Forces.

Adnan Afrin, spokesman and commander for SDF, told CNN that “more than 6,000 people have fled or left Baghouz within the past 48 hours and more are expected to arrive to the reception areas.”

Before the offensive started last month, SDF officials estimated that 1,500 civilians and 500 ISIS fighters remained, but as the assault got under way it became clear that the actual number was much higher.

SDF commanders have told CNN that ISIS fighters are putting up a fierce resistance in their bid to hold onto the group’s last scrap of territory, deploying guided missiles and using a network of tunnels to launch attacks.

The militants that are left include some of the most battle-hardened and experienced personnel remaining in ISIS. Some of those being used as human shields are the wives and children of those ISIS fighters.

Suspected ISIS fighters who fled Baghouz await processing.

The recapture of Baghouz would mark the end of ISIS’ territorial control and its so-called “caliphate,” which once covered large swaths of Iraq and Syria – an expanse about the size of Portugal.

At the group’s height, 7.7 million people were estimated to live under ISIS rule, according to Operation Inherent Resolve (CJTF-OIR), the official name for the coalition fighting ISIS.

In the years since its peak, the group’s annual revenue has more than halved: from up to $1.9 billion in 2014 to a maximum of $870 million in 2016, according to a recent report by the International Centre for the Study of Radicalisation and Political Violence at King’s College London.

Despite the loss of territory, and funds, a UN monitoring committee estimated in July 2018 that ISIS membership in Iraq and Syria was still between 20,000 and 30,000.

CNN’s Ben Wedeman and Kareem Khadder reported from eastern Syria, while Eliza Mackintosh wrote from London.