Ammonium nitrate
Security services found ammonium nitrate, metal splinters and a bottle containing TATP explosives at various locations, including the suspects' houses. Ammonium nitrate is used in fertilizer bombs. The metal splinters, used to cause more damage upon explosion, were brought home by one of the suspects from a metal workshop where he worked. The TATP was destroyed by bomb disposal experts due to the instability of the compound.