A lockdown has ended at Minneapolis public schools after police say a threat made on a social networking site turned out to be not credible.The district kept its 32,000 students indoors again Thursday and all exterior doors locked because of Internet threats traced to computer servers in Australia.Minneapolis police spokesman Jesse Garcia says someone called the city's 311 information line about 7:30 A-M Wednesday and warned that a posting on a social networking site said a male would be coming to an unspecified school to ``shoot up'' the place and then shoot himself.Garcia says police investigated and found ``the threat is not credible.''He says there have been no arrests.The FBI and Interpol have been notified.