A frame grab from a video released by the Islamic State shows an IS militant holding a knife before purportedly executing British aid worker David Cawthorne Haines. Islamic State Video/EPA /LANDOV hide caption

itoggle caption Islamic State Video/EPA /LANDOV

Thursday night in Midland City, Ala., there was a candlelight vigil for bus driver Charles Poland, who was killed Tuesday before a gunman snatched a 5-year-old boy — who is being held captive in an underground bunker. Philip Sears /Reuters /Landov hide caption

itoggle caption Philip Sears /Reuters /Landov

Islamist militants raided the In Amenas natural gas field (pictured) in Algeria on Wednesday and took several hostages. BP/AP hide caption

itoggle caption BP/AP