PHOENIX, AZ - Sheriff Joe Arpaio said tactical teams and detention officers have been on alert following reports that several white supremacists were planning a riot at Fourth Avenue Jail.

At least three inmates suspected of planning a disturbance were placed in lockdown Tuesday. Arpaio said those men were part of the "AZ 88 Boot Boys," a self-named white supremacist gang suspected of trafficking in methamphetamine and illegal weapons. The group was the target of a 14-month, multi-agency investigation that culminated in 42 indictments on gang, weapons and drug charges last week. Arpaio said word of a riot surfaced Tuesday.

"The intelligence we've been receiving is these guys don't like sleeping in the same cell with Blacks or Hispanics, and they're trying to cause problems in my jail," he said Wednesday.

Problem inmates are placed in "administrative segregation," which involves isolation for 23 hours a day. Other recognized white supremacists being held at the Fourth Avenue Jail have not been placed in isolation units. Arpaio said officials would continue to monitor the situation.