There are two simple rules to surviving a bomb attack: Remembering that where there's one bomb there are usually two; and to then do your "5s and 25s."
"There is literally nothing you can do about that first blast," says Milo Afong, a former Marine sniper who fought al-Qaeda in Iraq. "But if you're lucky enough not to be the one who gets destroyed, there's a couple things you can do to keep on living."
He says the first thing to do is drop to the ground and grip some turf.
"Then do an immediate ‘zero, five, and 25,'" he says.
These numbers represent the diameters of circles, around your position. The practice of checking zero, five feet, and 25 feet, in a circle, is one of the most basic ground infantry tactics in the military.
"So check zero first, which is directly under your feet," says Afong.
Then (carefully, slowly) check out to 5 feet, then out to 25, looking not only for casualties, but for any signs of "secondaries" — the bomber's second bomb.
"Where there is one, there are two," says Afong.
Nine times out of 10, there are follow-on bombs — so about the worst first thing you can do is run.
"They'll use that first bomb to funnel a terrified crowd into a kill zone, then detonate the second one," says Afong.
Afong says there's even a rule before the first two, especially in a crowd of civilians with no military training.
"First thing you do is take a deep breath, and think, 'stay calm,'" says Afong.
Stay calm. Assume there is a second bomb. Do your 5s and 25s. And you'll survive.