A 13-year-old boy has been left with cuts on his head after being struck with a blade, believed to be wrapped in tape, as he sat on a wall in Basin Road.
It happened at around 11.15am last Thursday (June 16) close to Chichester Police Station.
The attacker ran off in a westerly direction, while the victim went to school where they treated his injuries and called his parents.
A boy has been arrested and released on bail until Monday July 11.
Anyone who may have seen the attack, or has any other information, is urged to contact police online, or call 101, quoting serial 673 of 16/06.