The shooting was reported at 2:03 p.m. Friday and units have been sent to 838 Brannan and 888 Brannan, fire officials said.
David Karner, a customer service specialist at REI, a sporting goods and clothing store located at 840 Brannan St., said employees and customers have been ordered to shelter in place.
Other businesses nearby have also been asked to stay inside.
San Francisco police spokesperson Albie Esparza tells ABC7 News one suspect may still be at large.
Stay with ABC7NEWS.COM for updates on this developing story.