The Transportation Security Administration is warning transportation facilities and systems of a terrorist tactic involving an initial explosion designed to attract emergency and law enforcement personnel, followed by a stronger second blast intended to inflict maximum casualties.
“Transportation facilities and systems are particularly vulnerable to this type of attack because this tactic is well suited for locations that concentrate people in confined areas that have limited ingress and egress routes,” TSA said.
“For example, a small, concealed explosive, incendiary or nuisance device could be detonated on a subway platform at the height of rush hour, causing an evacuation to the street, where a secondary device or devices would then target evacuees and first responders.”
TSA said secondary explosive devices were typically hidden in out-of-site locations, camouflaged or contained in ordinary objects such as vehicles, briefcases, flowerpots or garbage cans.
Most secondary devices are initiated via time delay and are set to detonate in one hour or less after the first explosion. Command detonation via radio-controlled device or cell phone may also be used by individuals stationed within clear line of sight of the targeted area.