The bomber in the Manchester terrorist attack appeared to have carried a powerful explosive in a lightweight metal container concealed either within a black vest or a blue Karrimor backpack, and to have held a small detonator in his left hand, according to preliminary information gathered by British authorities.

The initial analysis of the bomb, based on evidence photographed and collected at the crime scene, does not specify the size or type of explosive used in the bomb’s main charge but suggests an improvised device made with forethought and care.

Possible detonator located in suspect’s left hand

Law enforcement images of metal nuts and screws propelled by the blast, and of damage nearby, show that the bomb’s makeshift shrapnel penetrated metal doors and left deep scuffs in brick walls.

Nuts and screws used as shrapnel

And a review of the location of those killed shows most of the fatalities occurred in a nearly complete circle around the bomber, Salman Abedi, whose upper torso was heaved outside the lethal ring toward the Manchester Arena entrance.

All of these are indicators of a powerful, high-velocity charge, and of a bomb in which its shrapnel was carefully and evenly packed.

Read the whole story from The New York Times.