WASHINGTON - An American man has been killed in Syria, a State Department spokesman said on Wednesday, declining to provide details.

Department spokesman Jeff Rathke identified the American as Keith Broomfield. NBC News reported Broomfield was in Syria fighting alongside Kurdish forces against Islamic State militants. Reuters could not immediately confirm why Broomfield was in Syria.

Social media accounts belonging to Kurdish fighters reported Broomfield’s death, saying he was killed near the border town of Kobani, NBC said. It added that the Kurdish forces, known as the Kurdish People’s Protection Union or YPG, have not officially confirmed the death. NBC said one Kurdish official told the news network that an American who had joined Kurdish fighters died fighting Islamic State but declined to give a name.

The report also cited Broomfield’s mother in Westminster, Massachusetts, who said she learned of his death from his brother and that Broomfield had left for Syria four months ago.

Moreover, thousands of people fled from Syria into Turkey on Wednesday as moderate rebels and Kurdish forces fought Islamic State insurgents holding the Syrian border town of Tel Abyad.

A Reuters photographer at the scene said the refugees had entered Turkey through a makeshift border crossing overseen by Turkish gendarmerie officers, and that many of them were women and children. A Turkish official said 2,000 refugees were being registered on Wednesday after more than 6,800 were admitted in the area last week.

He said they were fleeing advances by Kurdish YPG forces as well as aerial bombardment by the United States and Arab allies trying to help the Kurds push back Islamic State. The northeastern corner of Syria is important to the radical Islamist group because it links areas under Islamic State control in Syria and Iraq. The group last week launched an offensive on the provincial capital, the city of Hasaka, which is divided into zones run separately by the government of President Bashar al-Assad and a Kurdish administration. But Syria’s Kurds have also sought to take advantage of Syria’s complex war to expand their control over a region, stretching from Kobani to Qamishli, that they see as part of a future Kurdish state. Turkey, for its part, fears that this will encourage separatism in its own, adjacent Kurdish region.