Firefighters were dispatched to Westfield MainPlace mall at 10:13 a.m., a spokesperson for Orange County Fire Authority said. No injuries were immediately reported.
Seven people were injured Monday afternoon when a piece of ceiling tile fell on them at a shopping mall in Ontario.
Officials have given the all-clear following a major gas leak near the University of Southern California campus in Exposition Park.
CBS News consulted health experts who have identified the germiest spots in local malls.