Federal agents called LAPD about that suspicious device around 12:30 a.m. at 255 E. Temple Street, police said.
A police robot was seen checking through belongings outside the federal building.
There were no threats associated with the item, the LAPD said.
The investigation closed down Alameda Street from Commercial Street to Temple Street.
L.A. Metro put out a statement saying that their A Line is being affected by this incident and that bus shuttle service will be substituted for train service between Little Tokyo and the Arts District and Union Station.
No further details were immediately known.
This is a developing story. This article will continue to be updated as more information becomes available.
City News Service contributed to this report