From the San Francisco Chronicle:

By Michael Bodley, San Francisco Chronicle July 7, 2017

The fire that consumed an apartment and retail complex being built near downtown Oakland on Friday wasn’t the first to rip through a half-finished housing development in the area in recent years. It was the fifth.

While the cause of the latest blaze is not known, all four of the previous fires — including two at one site on the Oakland-Emeryville border — have been ruled arson by the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, said agency spokeswoman Alexandria Corneiro.