The fire was reported at 1:30 a.m. and quickly grew, eventually taking over the San Francisco Sausage Company building, which is the Columbus Salami company's slicing plant.
Smoke and flames poured out of the two-story building for hours. Crews decided it was too dangerous to go into the building to fight the fire so they are taking a defensive stand, with ladder trucks dumping water into the building.
The 30 employees in the building overnight were able to escape the building unharmed.
"We are fortunate and grateful that all of our employees are safe and accounted for," said Columbus Foods CEO Ralph Denisco. "We thank the South San Francisco Fire Department and other local fire departments for their quick response to this emergency."
The company said the buidling is used to slice and package Columbus Foods products and that it's working with vendors to ensure there is no significant disruption in its services.
They admit it will likely cause some shipment delays.
Columbus Foods has been a mainstay of the San Francisco meat industry for more than 90 years, originating the North Beach community of San Francisco. It produces a wide range of deli meat and cured meat products.