A teenage boy had a knife held against his throat when he was robbed by two men in Dorset.
The 17-year-old was in Castle Lane West, Bournemouth, when he noticed the driver of a gold Peugeot car look at him as he drove past early on Saturday.
About a minute later, he was grabbed from behind and the two men stole his black Nike rucksack containing a black wallet with cards, cash and house keys.
The men ran back to the Peugeot and were driven away.
The teenager was not hurt in the attack, in which he also had his Nokia 5800 touch screen phone stolen.
Det Con Steve May, of Bournemouth and Poole CID, said: "This is an extremely serious crime and I am determined to bring the cowardly robbers to justice.
"It may be that someone, perhaps several people, saw the vehicle speeding away or perhaps a person waiting in the vehicle as it was stationary along Littlecroft Avenue."
One of the robbers was white, aged in his 20s, just over 6ft (1.83m) and of stocky build. He was wearing a hooded top with the hood up.
The second robber is said to have olive, tanned skin and was also aged in his 20s. He was around 5ft 9ins (1.75m), of skinny build, with short dark hair.