As heavy rain from a large storm subsided, officials in Southern California said rock and mudslides remain a threat.

As heavy rain hit Southern California, the roof of a Smart & Final store in Azusa partially collapsed. The partial collapse happened with shoppers inside the store, but Azusa police says no injuries were reported and everyone was safely evacuated. It's unknown how many people were inside the store at the time.

The strongest storm of the season swept through Southern California on Thursday and drenched areas already scarred from the wildfires. FOX's Bill Melugin reports from Los Angeles.

Officials are grappling with the aftermath of the atmospheric river which caused mudslides and floods, especially in areas impacted by wildfires.

Pacific Palisades and Altadena are still reeling from last month’s devastating and deadly wildfires, but now there is a new concern for area residents: flooding. More than three inches of rain fell throughout the Los Angeles metropolitan area,