Police were called at 6:43 p.m. and told of numerous fights at the Westfield San Francisco Centre at 865 Market St.
The first officers to arrive called for backup, Officer Robert Rueca said. A number of fights were occurring as bystanders were watching.
Rueca said officers tried to detain several people some of whom resisted and would not obey officers. As officers attempted to stop the fighting, they were attacked and assaulted.
To help control the situation the mall was closed. Rueca said a number of people have been detained. One officer was injured.