the mountains saw another influx, as tens of thousands of people tried to escape the rapid advance of the Islamic State in Iraq and Syria, or ISIS, which now calls itself the Islamic State. Many of them were Yazidis, fleeing the town of Sinjar and surrounding villages in convoys of dozens of vehicles. The lucky ones used smuggling routes to cross into Syria and back into Kurdish-controlled areas of northern Iraq. The less fortunate were either seized by ISIS militants or headed into the mountains.

The Yazidi are an ancient religious sect -- mainly ethnic Kurds -- that worship an angel figure held by many Muslims to be the devil. ISIS has executed Yazidis who refuse to convert to its extreme ideology.

By Sunday, according to Iraqi and Kurdish sources,as many as 20,000 had been able to leave the mountains -- perhaps half of those who had been stranded for nearly a week. U.N. agencies estimated late last week there were as many as 50,000 people in the mountains.

Kurdish peshmerga forces appear to have secured an escape route, but a hazardous one with ISIS militants still roaming the area. According to some accounts, Syrian Kurds also helped people use parts of northeastern Syria under their control to reach Kurdish areas of northern Iraq.

U.S. airstrikes Saturday against several armored personnel carriers used by ISIS in the area may have helped the escape. But President Obama acknowledged Saturday that securing safe passage for those still stranded would be "logistically complicated."

Donatella Rovera of Amnesty International, who is in the region,