Griff Witte Karla Adam Sudarsan Raghavan The Washington Post

The investigation into a suicide blast that killed at least 22 people at a pop concert dramatically widened Wednesday, with security services on two continents rounding up suspects amid fears that the bombmaker who devised the bolt-spewing source of the carnage remains at large.

The investigation into a suicide blast that killed at least 22 people at a pop concert dramatically widened Wednesday, with security services on two continents rounding up suspects amid fears that the bombmaker who devised the bolt-spewing source of the carnage remains at large.

The investigation into a suicide blast that killed at least 22 people at a pop concert dramatically widened Wednesday, with security services on two continents rounding up suspects amid fears that the bombmaker who devised the bolt-spewing source of the carnage remains at large.

The investigation into a suicide blast that killed at least 22 people at a pop concert dramatically widened Wednesday, with security services on two continents rounding up suspects amid fears that the bombmaker who devised the bolt-spewing source of the carnage remains at large.