A 14-year-old boy is the second person arrested for allegedly setting a man on fire at an apartment on Lyell Avenue.
He, along with a 16-year-old boy, is charged with assault and arson.
Police say they sprayed the man with a flammable liquid as he sat in a chair, then lit the man on fire.
Both teens' identities are being withheld.
The unidentified elderly victim is in the burn unit in critical condition with second- and third-degree burns over most of his body.
Police say the suspect and the victim are not related, and it's not clear how they knew each other.