Olga Miranda, president of the SEIU Local 87 union, which represents thousands of janitors in the city, said immigration officials showed up at two buildings downtown on Friday. Federal immigration officials did not confirm the action when asked Monday. But an Immigration and Customs Enforcement, or ICE, official denied that the agency had any involvement in any action. Miranda declined to say which buildings were targeted, but said hundreds of her members who clean downtown offices stayed away from work Friday evening. Miranda said federal agents showed up in plain clothes and presented badges that said "Department of Homeland Security" to building security when asked, after initially being turned away. One set of agents showed up in the late afternoon carrying an arrest warrant for a specific person, but none of her members were arrested, Miranda said.