A man robbed two 15-year-olds after he threatened them with a knife and forced them to walk into a Northampton underpass.
The robbery happened between 7pm and 8.30pm on Tuesday, April 1 in Kettering Road, near the In and Out garage.
The two teenagers were walking along the road when a man approached and threatened them. He said he had a knife and told them to walk with him.
They walked up Kettering Road, turned right at Lumbertubs Inn and continued to an underpass on Lumbertubs Way, where the robber searched the boys and stole various items, including a phone and rucksack.
The robber is described as mixed race, 6ft, with a muscular build. He was about 20-years-old and had very close shaven hair. He was wearing dark green trousers with a bright yellow stripe down the side, a red short-sleeved top and blue trainers
Witnesses or anyone with information are asked to contact Northamptonshire Police on 101. Alternatively, information can be given anonymously to Crimestoppers on 0800 555 111.