Firefighters were dispatched to the scene at 107th Street and Avalon Boulevard at 4:17 a.m., according to Brian Humphrey of the Los Angeles City Fire Department.
A watch commander at the Los Angeles Police Department's Southeast station said police were conducting a criminal threat investigation, just prior to the fire.
"It's a domestic type situation,'' he said.
Officer Mike Lopez of the LAPD's Media Relations Section said the fire department was investigating the cause of the fire and police were investigating if it was related to the criminal threat allegation.
No details were available about the relationship between the reporting party and the person who allegedly made the threat, Lopez said.