The police stated that one of the arrested men ordered three metric tonnes ( 6,600 pounds ) of ammonium nitrate fertilizer , a potentially powerful ingredient often used as quarry and mining explosives . This weight has widely been compared to the amount of ammonium nitrate used in the 1995 Oklahoma City bombing in the United States . The official account estimates the ammonium nitrate in the Oklahoma City bomb at 2,000 pounds , or about 0.9 metric tonnes . There was not any imminent danger to the public , as a harmless substance was substituted for the ordered ammonium nitrate and delivered to the men by INSET officers in a sting operation
Oklahoma City bombing
Oklahoma City bombing
2006 Ontario terrorism plot