The San Francisco Fire Department tweeted that the single story warehouse was burning at 1300 Donner Street.
Firefighters battled the blaze inside the 5,000 square foot warehouse, and a shelter in place order was made around 2:20 p.m. due to toxic smoke from the fire.
"The concern is that there may be some toxic air," SFFD Chief Joanne Hayes-White said.
Neighbors in the area say the fire started with a boom. "It was like a cherry bomb," one neighbor said.