The number of Christian Assyrian hostages taken by the Islamic State (IS) this week has increased to 262.

The militants seized nearly a dozen villages in northeastern Syria through Wednesday night.

Assyrian Human Rights Network founder Osama Edward reported that 11 villages were attacked over the course of three days. 

"ISIS is taking over more and more Assyrian towns," he lamented. 

The number of hostages climbed from initial reports of 70-100, to 150, to the Network's estimate of 262 men, women, and children kidnapped. The London-based Syrian Observatory for Human Rights estimated 220 missing in a statement released Thursday. 

The villages targeted were in the Tal Tamer area in al-Hasakah Province, and the Observatory believes the hostages were taken to to the Mount Abdelaziz area, southwest of Tal Tamer.

In addition to the hundreds captured, thousands were forced to flee their homes. The villagers were already without basic necessities such as water, clothing, and food because of the ongoing Syrian Civil War, Edward said. 

A Modesto, California couple said they have family members in the Tal Tamer area, and fear that 12 of them were taken by IS.

"We pray, we pray all the time," Sharlet and Romel David told KCRA.

"What we've heard is it was like a sea of black uniforms marching through all the villages, burning down the churches, desecrating the crosses and wreaking havoc.

"I just want them to be safe," Sharlet insisted. 

The Sunni Muslim extremists have persecuted, raped and killed Christians and Shiite Muslims across Iraq and Syria in an increasingly deadly campaign over the past four years.

Churches and Shiite shrines have been bombed, and millions of Iraqis and Syrians have fled the area because of the wanton violence.