A 15-year-old boy has been arrested on suspicion of grievous bodily harm with intent after a man was stabbed outside Worthing train station on Friday, said police.
Police said the suspect was later bailed, while the victim, a man in his 20s, remained in hospital in a stable condition.
A police spokesman said two men were seen running down Railway Approach around 8.10pm on September 21, when a physical altercation occurred.
The victim suffered serious injuries, believed to have been caused by a knife, police said.
Prevention Inspector Allan Lowe said: “This violence is obviously distressing but I can assure local people that we are doing all we can, taking targeted action to help keep them safe.
“I understand that residents will be concerned by violence taking place in the town but I want to reassure everyone that their safety is our priority.
“We want to speak to anyone who may have witnessed the incident to get in contact with us.
“No-one knows their neighbourhoods better than residents themselves, so please get in touch if something seems suspicious or out of place.”