Paul Lom, a 35-year-old San Jose man, succumbed to his injuries on Thursday, according to police.
The explosion occurred at about 5:15 p.m. last Saturday at an apartment at 3624 Silver Oaks Way. Evan Aviles, 21, and his girlfriend Lexie Huston, 22, who lived at the apartment, remain in critical condition, police said.
Livermore police Lt. Mike Peretti said illegal drug paraphernalia was found in the apartment and was likely a factor in the fire, but the apartment was not a methamphetamine lab.
Four other families who lived in the apartment building have been relocated pending a building inspection to ensure that the structure is sound enough for them to return, police said.
Police detectives said they are still actively investigating the case and the cause of the fire.
They said the cause of the explosion has not yet been determined and nothing has been ruled out at this time.