(Reuters) - Three people were found dead inside a Los Angeles-area business on Saturday in what might have been a fire bomb or Molotov cocktail attack, law enforcement said.

One victim was alive but covered in flames when firefighters arrived at the early morning blaze in the city of El Monte, east of downtown Los Angeles, said Los Angeles County Sheriff's Department spokeswoman Grace Medrano.

Firefighters were unable to get to the man, trapped behind a heavily locked gate, before he died from his injuries, she said.

Inside the building, two other bodies were found, she said. One firefighter sustained injuries to his face while trying to rescue the burning man, she said.

The sheriff's office did not release the name of the business, but the Los Angeles Times said it was a tire shop.

A witness who called 911 told authorities he saw several suspects throw a Molotov cocktail at the business before driving away, Medrano said.

Fire officials were working to determine whether the business was hit by a Molotov cocktail or fire bomb, she said.

No arrests have been made, she said.

(Reporting by Victoria Cavaliere; Editing by Michael Perry)