Few details were available, but police and fire officials were responding to the store in the 6750 block of Fallbrook Avenue in West Hills.
The incident occurred around 3:45 p.m. in the parking lot of Fallbrook Center, a retail complex that is also home to a Target, Home Depot and Walmart.
A law enforcement source said an early report indicated that at least three people were wounded and that police had detained one person.
This is a developing story. It will be updated soon.