Islamic State fighters may have captured up to 3,000 fleeing Iraqi villagers on Thursday and subsequently executed 12 of them, the U.N. refugee agency UNHCR said in a daily report on events in Iraq.

The report followed a statement on Thursday from the Iraqi Observatory for Human rights, which said about 1,900 civilians had been captured by an estimated 100-120 Islamic State fighters, who were using people as shields against attacks by Iraqi Security Forces. Tens of civilians had been executed, and six burnt.

Read more: Reuters