Canadian police foiled a homegrown terrorist attack by arresting 17 suspects, who obtained three times the amount of an explosive ingredient used in the Oklahoma City bombing, officials said Saturday. The Associated Press quoted FBI as saying that the Canadian suspects may have had "limited contact" with two men recently arrested on terrorism charges in Georgia. About 400 regional police and federal agents participated in the arrests Friday and early Saturday. "These individuals were allegedly intent on committing acts of terrorism against their own country and their own people," Prime Minister Stephen Harper said in a statement. "As we have said on many occasions, Canada is not immune to the threat of terrorism." The Royal Canadian Mounted Police arrested 12 adult suspects, ages 43 to 19, and five suspects younger than 18 on terrorism charges including plotting attacks with explosives on Canadian targets. The suspects were either citizens or residents of Canada and had trained together, police said. The group acquired three tons of ammonium nitrate — three times the amount used to blow up the Murrah Federal Building on April 19, 1995, in Oklahoma City, killing 168 people and injured more than 800, said assistant Royal Canadian Mounted Police commissioner Mike McDonell. The fertilizer can be mixed with fuel oil or other ingredients to make a bomb. "This group posed a real and serious threat," McDonell said. "It had the capacity and intent to carry out these attacks."