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"Initial inquiries have shown that an explosive product made up of nitrate and ammonium and two TATP explosives, and also with nails and the explosion was set off from a distance," Taeb Cherkaoui said.
Triacetone triperoxyde, or TATP, is relatively easy to make and has surfaced in a number of recent investigations into attacks, including bombings in the Middle East and the July 2005 London bombings.