Gunmen dressed as police commandos kidnapped up to 150 staff and visitors in a lightning raid on a Baghdad research institute Tuesday, the largest mass abduction since the start of the US occupation. Hours later, the Interior Ministry said three of the kidnap victims were apparently set free and found unharmed along eastern Baghdad's Palestine Street. Ministry spokesman Brig. Abdul-Karim Khallaf, told The Associated Press the police chief of the Karradah neighborhood where the kidnappings occurred has been placed under investigation along with some of his officers. The fate of the remaining kidnap victims remained unknown. Iraq's higher education minister immediately ordered all universities closed until security improvements are made, saying he was "not ready to see more professors get killed.