Four teenagers were arrested in connection with an incident at a petrol station in Bognor.
Police were called to the Esso garage in Chichester Road, Bognor, shortly after 7pm on January 6.
A group of youths were seen entering the store, with one attempting to climb over the counter inside to threaten a staff member.
Two youths were detained at the scene by a member of the public and a staff member, while the other two ran away as police arrived.
One boy was arrested on suspicion of aggravated burglary, robbery, and common assault.
Another boy was arrested on suspicion of aggravated burglary.
The third boy was arrested on suspicion of conspiring to commit robbery.
The fourth boy was arrested on suspicion of aiding or abetting a burglary.
The boys, all aged 15, have since been bailed, pending further enquiries.
Officers investigating are appealing for witnesses or anyone with information about what happened to come forward.
Information can be reported to Sussex Police online or on 101, quoting serial 1202 of 13/01.
