LAPD officers responded to the Baldwin Hills Crenshaw Plaza on Wednesday afternoon after a report of shots fired.
The call came in just after 7 p.m. in the 3700 block of Santa Rosalia (map), according to L.A. Fire Department spokesman Brian Humphrey.
Aerial video from the scene showed a security guard outside the mall preventing shoppers from entering the building.
One person attending a conference in the plaza's community room told KTLA that everyone was initially told to get down on the floor and stay put.
After about a half hour, those inside were told they could leave, he said.
The gunman allegedly shot at a security guard outside the mall, but missed, according to LAPD Commander Andy Smith.
Officers set up a perimeter to search a neighborhood near Vernon Avenue and Crenshaw Boulevard for the gunman, aerial video showed.
The video appeared to show a confrontation involving officers and the alleged gunman around 8:25 p.m. inside a residential garage on Angeles Vista Boulevard.
A body was later seen being taken out of the building on gurney and loaded into an ambulance.
No further information was released.