Kurdish fighters have taken control of the border town of Tal Abyad, dealing a significant blow to Islamic State’s ability to wage war in Syria by cutting off a supply line to its self-proclaimed capital of Raqqa.

A senior Kurdish commander, Haqi Kobane, said on Tuesday that the Kurdish YPG militia units that he leads, along with their allies from the Free Syrian Army, were starting to clear booby traps and mines in Tal Abyad. The Isis had been in control of the town on the Turkish border for more than a year.

“Daesh has been broken at the hands of the YPG ... It is a victory for all Syrians,” he said by phone from northern Syria, using the Arabic acronym for Isis.

The Kurdish advance has displaced 23,000 people who have fled to Turkey to escape the fighting, according to the United Nations’ refugee agency, UNHCR.

An Associated Press team on the Turkish side of the Akçakale border crossing said a large black and white Isis flag was taken down on Tuesday in Tal Abyad and replaced with a yellow, triangular YPG flag.

The border was calm, in sharp contrast to previous days when thousands of Syrians poured through, some making a hole in the fence to break into Turkey. On Tuesday, a few civilians were seen walking around, along with some people on the Turkish side apparently waiting to go back into Syria.

The UK-based Syrian Observatory for Human Rights monitoring group also confirmed on Tuesday that the YPG seized Tal Abyad with help from the Free Syrian Army.

The takeover of the town marks the biggest setback yet for Isis and puts even more pressure on Raqqa by depriving the group of a direct route for bringing in foreign fighters and supplies, as well as linking the Kurds’ two fronts,.

The US provided air cover for the Kurdish advance, launching concentrated air strikes that targeted Isis fighters inside and along supply routes.

The Isis defeat in Tal Abyad is a stunning reversal of fortunes for the group, which only last month captured the provincial capital of Ramadi in Iraq’s Anbar province and the historic town of Palmyra in central Syria.

The jihadi group still controls about a third of Iraq and Syria, including the second-largest Iraqi city, Mosul. Extremist fighters continue to battle Iraqi security forces and Shia militias for territory north and east of the capital, Baghdad.

On Tuesday, Iraqi officials said families began returning to Tikrit two and a half months after security forces backed by Shia militias drove Isis out of the Sunni city.

The governor of Iraq’s Salahuddin province, Raed al-Jabouri, said about 200 families, who spent the past months either in makeshift camps or half-built and abandoned buildings outside Tikrit, had returned to the provincial capital the day before.

He added that more than 1,000 families were expected to return on Thursday.

His deputy, Ammar Hikmat, said public services inside the city were still struggling owing to military operations and that authorities were working to restore them. The main challenge was electricity, he said, as the national grid offered less than 10 hours a day of power and many of the generator plants outside Tikrit were not working. Drinking water was available for about 80% of the city.

Jabouri and Hikmat said work was still under way to compensate those who have had their properties damaged.

State television aired footage of security forces guarding buses packed with people, some waving Iraqi flags. Some residents could be seen embracing members of the security forces when they reached Tikrit, Saddam Hussein’s hometown, while others fired rifles into the air in celebration.

Isis captured Tikrit last summer during its sweep across the country. Iraqi forces managed to retake it following weeks of intense fighting and US-led air strikes, marking their biggest gain yet against the extremist group in Iraq.

According to Iraq’s migration and displaced people ministry, about 400,000 people fled Salahuddin since Tikrit fell in June 2014. Some families have trickled back to liberated areas outside Tikrit, but this the first time they have returned to the city.

After retaking Tikrit in April, officials said it would take time for people to return because bombs needed to be cleared, police stations opened and services restored.