The man was caught on surveillance camera starting a fire under a couch in the leasing office of the Axis 2300 apartment complex on Wednesday.
The flames produced a thick smoke on the first floor, but responding firefighters quickly doused the blaze.
As most of the residents evacuated the building, one male resident returned to his apartment to get his keys. That's when he found a suspect inside, apparently burglarizing his apartment. During the confrontation, the suspect pepper-sprayed the resident and fled.
Damage from the lobby fire was minimal and the resident was treated at the scene.
The suspect is described as a man around 25-35 years old with dark complexion - possibly Hispanic or Middle Eastern. Officials say he is 5 feet 9 inches to 6 feet tall with a heavy build and dark, curly hair. He was wearing a black leather jacket, light blue jeans, tan shoes and carrying a black backpack. One witnesses said he had a mole on his cheek.
There is also a second person of interest who was seen in the area and might have information. That subject is described as a man around 40-50 years old with dark complexion and a white goatee. He was seen wearing a black beanie, black jacket, blue jeans and carrying an orange and black backpack.
Detectives are working to determine if there may be additional arsons related to this case.
If you have any information that can help investigators, you're urged to call Irvine police at (714) 573-6712.