Multiple fatalities in apparent sniper attack on Dallas ICE facility... [View all]

Three detainees were shot at the Dallas Immigration and Customs Enforcement field office during a movement in the facility's sally port on Wednesday morning, law enforcement sources told ABC News.

"Multiple" victims are dead, acting ICE Director Todd Lyons told ABC News, while Dallas police said one person was killed and two were hurt.

The shooter -- who appeared "to be a sniper from an elevated position" firing from "a couple hundred yards" away -- died from a self-inflicted gunshot wound, Lyons said. Dallas police said it appears the shooter fired from an adjacent building.