A man claiming to have a bomb in a canvas bag took at least one woman hostage Friday in an office building in Pittsburgh, Pennsylvania, the FBI said. \"There\'s a hostage situation at Three Gateway Center,\" said Kelly Kochamba, an FBI spokesperson in Pittsburgh, naming the building in a downtown office complex. \"There\'s at least one woman, I don\'t know if there\'s any more than one.\" The assailant claimed to have a bomb, \"but there is no evidence at this time,\" Kochamba said.