The mass arrests of Japanese Americans began the evening of the Pearl Harbor attack:
"As the arrests began last night, Attorney General Francis Biddle announced that FDR had authorized him to apprehend as 'alien enemies', Japanese aliens considered dangerous 'to the peace and security of the U.S.A. He said that at least 1,000 Japanese nationals would be affected, but there would be 'a fair hearing for all persons apprehended.'... In Los Angeles' Little Tokyo, largest Japanese colony in the USA, the FBI arrested three men and a woman in a hotel. Other groups of FBI agents were reported circulating through the area and taking alien Japanese into custody."
