(CNN) -- Hundreds of Kurdish fighters from Turkey have arrived in the Syrian Kurdish town of Ayn al-Arab to join a Kurdish militia group battling to hold off ISIS forces, activists said Saturday.
Clashes continue in the area between the militia, called the People's Protection Unit (YPG,) and the ISIS fighters, according the London-based Syrian Observatory for Human Rights.
The latest ISIS advance in Syria has brought a swath of the country's north-central Kurdish region under siege, with Kurdish leaders warning of another humanitarian crisis without international intervention.
The Syrian Kurdish town of Ayn al-Arab, or Kobani as it is known to the Kurds, is an island, surrounded by ISIS on three fronts and the Turkish border to the north.
The town was already mostly blockaded by ISIS, but in the past several days some 60 nearby villages fell under ISIS control, according to the Syrian Observatory for Human Rights.
ISIS, which refers to itself as the Islamic State, took 39 villages on Friday alone as Kurdish forces withdrew from their positions, the Observatory said.
Mostafa Baly, a Kurdish activist inside Ayn al-Arab, told CNN on Saturday that there had been fierce clashes between ISIS and the YPG 20 kilometers to the east and south of the town, and 25 kilometers to the west.
"The conversation is no longer about withdrawing from this village or taking control of that place. For the People's Protection Unit it is about resisting the attack by ISIS and defending 50,000 Kurds from a massacre," he said.
Hundred of Kurdish fighters are streaming in from Turkey to join fighters on the front lines and more continue to cross into the city as the minority prepares for what it believes will be an existential battle.
"The Kurdish people do not want to go to the refugee camps. We refuse to live in tents. the only option is to stand strong and defeat ISIS," he said.
News of the Kurdish fighters flooding to join the defense of Ayn al-Arab came as Turkey's government announced that 49 hostages seized from the Turkish consulate in Mosul, Iraq, had been freed after three months in captivity.
Fears of a humanitarian crisis in Ayn al-Arab rose this week as displaced people sought refuge there but became trapped between the fighting and the Turkish border.
Turkey finally opened its border on Friday, relieving some of the mounting pressure in Ayn al-Arab and allowing refugees to enter its southeastern Sanliurfa province.
Deputy Prime Minister Numan Kurtulmus said Saturday that some 45,000 Kurds fleeing the violence had entered Sanliurfa and neighboring Gaziantep provinces on Friday, according to Turkey's semi-official Anadolu news agency.
The refugees entered through eight checkpoints along the border and are being housed in tents, he said.
"In no other place in the world, no country, regardless how good their economic conditions are, could accommodate some 45,000 refugees at one time. This shows the strength and good intentions of Turkey," Kurtulmus is quoted as saying.
Hosting Syrian refugees is nothing new for Turkey and other neighboring nations. About 815,000 registered Syrian refugees were in Turkey as of last month, part of the 3 million total registered Syrian refugees the U.N. has counted amid Syria's three-year civil war.
A further 6.5 million people were believed to be displaced within Syria as of last month, according to the United Nations.
Masoud Barzani, President of Iraq's semiautonomous Kurdistan Region, called the ISIS attacks in northern Syria "barbaric" and described them as ethnic cleansing.
"I ask the international community to take every measure as soon as possible to save Kobani and the people of Syrian Kurdistan from the terrorists," he said in a statement Friday. "The ISIS terrorists perpetrate crimes and atrocities wherever they are, therefore they have to be hit and defeated wherever they are."
CNN's Mariano Castillo contributed to this report.