Firefighters say the leak started just before 8 a.m. at the Milk Specialties Global Plant on Divisadero Avenue near Goshen Avenue.
Authorities sent a reverse 911 call to residents within a half mile radius to the north and west, asking them to stay inside, close their windows, and avoid using air conditioning.
That order was lifted about five hours later after crews stopped the leak. Fire officials say the cause was a corroded valve.
