Officials were looking into whether the explosion, which killed three sheriff’s deputies, was caused by devices seized from a condo in Santa Monica a day before the blast.
It was not immediately clear what caused the blast at the Los Angeles County Sheriff’s Department’s Biscailuz Training Academy center. No one else was injured, officials said.
An A.C.L.U. lawyer said it was possible that any sheriff who complied with the request could be in violation of California’s so-called sanctuary state law.
Sheriff Robert Luna of Los Angeles County, third from right, with deputies in Altadena, Calif., in January. His agency signaled it would not honor a request the Justice Department’s request for the names of noncitizen inmates.