As Iraqi forces close in on Mosul, ISIS appears to be stepping up its atrocities in the city. A senior intelligence source tells CNN that the group rounded up and killed 284 men and boys in southern Mosul on Thursday and Friday. The victims, including children, are believed to be "human shields" the group had been using to try to avoid attacks, the source says. The United Nations says it believes hundreds of families from outlying villages have been forced into the city to serve as human shields for the militants, and it is investigating reports that 40 people were massacred in one village.
ISIS is believed to be killing civilians it suspects of disloyalty, and there are fears the group will kill more of its human shields rather than see them liberated, UN officials warn. The BBC reports that US Defense Secretary is in Baghdad on an unscheduled visit. It's not clear whether he will visit American troops closer to Mosul, where soldiers at one base have had to don masks because of fumes from a sulfur plant set alight during fighting. The AP reports that the Pentagon has identified the first American killed in the Mosul offensive as Jason C. Finan from Anaheim, Calif. He was killed by a roadside bomb while advising Kurdish peshmerga forces north of the city. (Read more ISIS stories.)