Officers responded to the report at 9:40 a.m. at 700 Exposition Park Drive, near the intersection of Exposition Boulevard and Figueroa Street, a spokesperson for the Los Angeles Police Department told ABC7.
Video from AIR7 showed a canopy set up over the body of the deceased suspect, just steps away from the museum building. What appeared to be a gun was seen near the canopy.
There were no reports of any injuries to police officers.
Witness Stacey Hutchinson said the suspect, with rifle in hand, gave him a fist bump and nonchalantly sat down at a bench outside the California Science Center before the shooting unfolded.
Hutchinson said LAPD officers approached the suspect.
"They confronted him with bean bag guns...they dropped the bean bag guns when the perpetrator got up off the bench and grabbed the gun," he described. "As he picked up the gun and pointed it at officers, they opened fire."
Police said they're investigating why the man was at the location with a weapon.
The California Science Center was placed under a brief lockdown. It's expected to resume normal operations Friday.