Canadian authorities decided to move quickly against a suspected homegrown terror ring and head off any attack on Ontario targets after undercover Mounties delivered bomb-making materials in a sting operation, according to a news report Sunday. The Toronto Star said the Royal Canadian Mounted Police itself delivered the three tons of ammonium nitrate that authorities reported Saturday had been acquired by a group of Muslims apparently inspired by al-Qaida. Once the deal was done, police moved in for the arrests, the Star said. It added that investigators had learned of the group's alleged plan to build a bomb and then controlled the sale and transport of the fertilizer. Authorities refused to discuss the Star's story. They have revealed few details of the purported plot, news of which was followed by vandalism against at least one mosque and e-mailed threats to Muslim leaders.