According to witness reports, Oakland, Calif., warehouse fire had been burning for some time before people on 2nd floor were alerted, officials say
ATF official says refrigerator has not been determined to be cause of Oakland, Calif., warehouse fire; investigation into cause is ongoing
Officials say fire started on 1st floor of Oakland, Calif., warehouse; smoke trapped people on 2nd floor
No evidence of fire alarm system or fire suppression system in Oakland, Calif., warehouse, officials say