SAN FRANCISCO (AP) -- Fire investigators say a fire that caused $2.4 million worth of damage to an empty warehouse on San Francisco's waterfront in June was caused by workers prepping the building for America's Cup yacht race next year.

Fire Department spokeswoman Mindy Talmadge told the San Francisco Chronicle that the June 20 blaze on Pier 29 was sparked by welders who accidentally ignited some wood.

America's Cup organizers have said they don't expect the blaze to have any impact on plans for the site.

In a separate investigation, San Francisco fire officials say an apartment building fire last week that killed a 78-year-old man was started accidentally.

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