A man was robbed at knifepoint by "a gang of eight or nine" in Northampton.
The group approached him and ordered him to hand over his phone.
When he refused, one of the gang pulled out a 20cm hunting-style knife and pointed it at the victim who then ran off.
The incident took place in Talan Rise, Blackthorn, Northampton on February 18 sometime between 3pm and 3.50pm.
The main suspect was described by police as mixed race, aged about 18, 6ft, with a medium/stocky build. He had a goatee-style beard and he had four large plaits in his hair, two at the front and two at the back. He was wearing a black beanie-style hat with a badge or motif on the front, and a black puffa jacket.
The other gang members were either mixed race or white males, all aged 16-20 and all wearing dark-coloured or black sports clothing with hats and gloves. Some of the group were riding bikes.
Anyone with information should call Northamptonshire Police on 101 or, alternatively, call Crimestoppers anonymously on 0800 555111