Since Thursday, 20,000 Syrian refugees have fled across the border into Iraqi Kurdistan—10,000 of them on Saturday alone.

The UNHCR doesn't know why the sudden exodus has occurred this weekend specifically, reports the BBC, though clashes between Syrian Kurds and anti-government Islamic militants have been increasing in recent months.

Food and work are also increasingly scarce in Syria's Kurdish majority areas, and most of those fleeing into Iraq are women, children, and the elderly, reports the AFP.

"There was war and looting and problems," says a man who fled with his five kids. "We did not find a morsel [of food], so, with our children, we came here."

Charity Save the Children has launched an emergency response to accommodate the influx of arrivals, reports the BBC. "This is an unprecedented influx of refugees, and the main concern is that so many of them are stuck out in the open at the border or in emergency reception areas with limited, if any, access to basic services," says a Save the Children team leader.

The number of Syrians who have fled since the start of the war has now hit 1,916,387, the UN says in a press release, and two-thirds of those left this year.