Police have appealed for information after a group of six teenage boys were robbed in Rose Green.
The incident happened in Sefton Drive sometime between 10.00pm and 10.50pm on Wednesday, September 7.
The group of teenagers, all aged 15 or 16, were walking past the Murco Garage in Hewarts Lane when they heard yells from a car.
They continued on their way into Rose Green Road and entered Sefton Road, where they were approached by two men who threatened them with a knife and a handgun before stealing their mobile phones. One of the boys was hit in the face.
Detective Constable Kevin Etheridge from West Sussex CID said: “It is not clear whether the gun was an imitation weapon, but the victims were left extremely shaken and are being offered our support.
“Specially trained officers were quick to respond to reports of a firearm being used and conducted a search of the area.
“This appears to be an isolated incident near to a busy service station and I am keen to speak to anyone with information, including the people travelling past in a car prior to the robbery who may have information that could assist the investigation.
“Officers from Arun neighbourhood policing team have increased patrols in the area, are making house-to-house inquiries and are viewing CCTV as part of the ongoing investigation.”
Anyone with information is asked to call Sussex Police on 0845 60 70 999 quoting serial 1722 of 7/9 or anonymously to the independent charity Crimestoppers on 0800 555 111.