Officers found a man inside the apartment armed with a handgun.
Police secured the apartment and tried to make verbal contact with the 23-year-old male through a partially opened front door.
As police tried to communicate with the subject, the man appeared pointing a black-semi automatic handgun and a large kitchen knife at officers and shooting ensued, according to the Riverside Police Department.
Medical aid was immediately summoned. However, the man was pronounced dead at the scene.
His identity is being withheld pending notification of kin.
Detectives from the Homicide Unit are conducting an investigation into the incident, as is standard procedure with all officer-involved shootings.
Anyone with information regarding this case is urged to contact Detective Rick Cobb at (951) 353-7135 or Detective Rick Wheeler at (951) 353-7134.