A landscaping project accident caused the partial collapse of a residential parking structure in the Century City area of Los Angeles.
No injuries were reported after the Friday morning incident but urban search-and-rescue units were dispatched as a precaution, and two buildings were evacuated.
Fire Department spokesman Eric French said construction crews were using earth-moving machines to handle lava rock and dirt, but the weight of the material was too much for the structural integrity of the parking garage.
Firefighters initially believed a large planter had fallen from a crane, but French said later that neither was involved.
This story has been updated.