Australian Federal Police Acting Commissioner Andrew Colvin, left, and New South Wales Police Commissioner Andrew Scipione, right, describe how 800 federal and state police officers raided more than two dozen properties as part of the operation in Sydney, Thursday, Sept. 18, 2014.SYDNEY - Australia's prime minister says intelligence that Islamic State supporters were planning to carry out a killing to demonstrate its abilities led to counterterrorism raids in Sydney.
Australian police detained 15 people Thursday in a major counterterrorism operation, saying intelligence indicated a random, violent attack was being planned in Australia.
Prime Minister Tony Abbott told reporters that "exhortations" were coming from an Australian who is senior in the Islamic State movement to support networks in Australia to "conduct demonstration killings." He did not name the Australian.
Police say 800 federal and state police officers raided more than a dozen properties across Sydney as part of the operation - the largest in Australian history.
Police say one person was charged with serious terrorism-related offenses and was scheduled to appear in court Thursday.