A U.S.-led alliance launched airstrikes against Islamic State on Thursday in an area of northeast Syria where the militants are now estimated to have abducted at least 220 Assyrian Christians this week, a group monitoring the war reported.

The Syrian Observatory for Human Rights said the airstrikes targeted Islamic State fighters near the town of Tel Tamr, where the militants, also known as ISIS, had captured 10 Assyrian villages.

A prominent Syrian Christian, Bassam Ishak, told Reuters: “Some people have tried to call them by cellphone, the relatives that have been abducted, and they get an answer from a member of ISIS who tells that they will send the head of their relative. […]