Police are appealing for witnesses after a group of youths were robbed at knifepoint.
The four victims were sitting on a bench close to a stream in Scrase Valley Nature Reserve, between Backwoods Lane and Wilmington Way in Haywards Heath, when they were approached by three men.
One of the trio pulled out a knife and ordered the victims to hand over their mobile phones at around 9pm on Sunday 18 August.
The first thief was white, about 17, six foot and skinny.
He was wearing a black and grey hooded top, jeans and a snap back flat peaked baseball cap.
He spoke with a London accent.
The second thief was white, 5ft 10in and skinny with Justin Bieber-style brown hair. He was wearing a hoodie with the hood up.
The third thief was white, 5ft 8in, skinny and about 15. He was wearing a black hoodie and dark coloured trousers.
Police are keen to speak to anyone who recognises the description of the thieves or who saw what happened.
Anyone with information should call 101 quoting serial 8 of 19 August or the independent charity Crimestoppers anonymously on 0800 555111.