The blaze was ferocious; smoke and flames lit up the night sky just after midnight. It sent neighbor Michael Serafino running from his home.
"You could see the ball of fire, I thought holy smokes. I grabbed my wife and she grabbed her laptop and her phone and we were gone across the street," said Serafino.
The blaze happened on the campus of school. The portable buildings that burned were going to be temporary offices for the San Leandro School District, which shares the same property. They were delivered only yesterday.
"Really unfortunate, that was going to be temporary office space for us to move into next week for our district office renovation," said San Leandro Unified School District Spokesman John Thompson.
"Hopefully this is some kind of accident and not something malicious," said James Madison Elementary Principal Gary Grotke.
But officials suspect arson; the buildings were so new, not even the power had been connected yet.
"Right now, with there not being any electrical sources and (the portables) just being delivered, it would go in that direction of being suspicious," said Alameda County Fire Department Chief Charles Palmer.
As investigators search for a cause, neighbors and school officials are relieved the intense fire didn't spread to homes and the school.
Fire investigators are going to comb every inch of the rubble looking for a cause. The buildings were rented. The district hopes it can find temporary offices someplace else. Classes at the school were not affected by the fire.