Someone planted a facsimile of a bomb in a Century City office tower and called in a threat, causing police to evacuate at least part of the building, authorities said today.

The threat to 1901 Avenue of the Stars was called in just before 4 p.m. Thursday, according to police spokesmen.

As police searched the 20-story building, they found a "suspicious item" in a restroom on the 16th floor, Los Angeles police spokesman Officer Jason Lee said.

Lt. Howard Leslie of the LAPD's West Los Angeles Station said the item was made to look like a bomb but posed no threat.

Bomb squad officers spent several hours at the building, and Leslie said the LAPD's criminal conspiracy unit would pursue suspects in the case.

The building's tenants include Sheppard, Mullin, Richter & Hampton, a major law firm occupying Suite 1600.