Boyle Heights commercial building fire

Firefighters battle a stubborn fire that raged in Boyle Heights early Thursday morning, causing extensive damage to a commercial building containing four businesses in the 3700 block of Whittier Boulevard.  (Lawrence K. Ho / Los Angeles Times)

Firefighters battle a stubborn fire that raged in Boyle Heights early Thursday morning, causing extensive damage to a commercial building containing four businesses in the 3700 block of Whittier Boulevard.  (Lawrence K. Ho / Los Angeles Times)

Firefighters from the Los Angeles Fire Department survey the damage done to several businesses destroyed by an overnight fire in the 3700 block of Whittier Boulevard in Boyle Heights.   (Mark Boster / Los Angeles Times)

Firefighters from the Los Angeles Fire Department survey the damage done to several businesses destroyed by an overnight fire in the 3700 block of Whittier Boulevard in Boyle Heights.   (Mark Boster / Los Angeles Times)