Keep back
Definition 1 of 3
Pro Tip 1/3Physical Space
Use 'keep back' to maintain a safe or respectful distance in physical spaces. 
During the concert, fans were asked to keep back from the stage.
Pro Tip 2/3Security Measures
'Keep back' often relates to safety and security advice or instructions. 
The signs near the cliff warned hikers to keep back.
Pro Tip 3/3Authority Commands
Authorities use 'keep back' to control crowds or manage a scene. 
The firefighter shouted to keep back from the burning building.