A teenager was beaten by a group of youths as he was robbed for the second time in the same evening on Sunday.
The 15-year-old was on the ramp in George Street leading into The Mall at about 5.30pm when he began to speak to two men.
They demanded he hand over £10 and he refused and began to walk away, but the offenders grabbed him and during a scuffle took his black Nike zip-up hooded top.
The victim chased the robbers along Upper Wellingston Street before he lost sight of them.
They are described as men of Asian apperance, aged 15 or 16, and it is believed they used the names Tabe and Dudley.
Three hours later, the victim was in the Namco Station Arcade in The Galaxy Centre when two victims approached him and asked him to follow them outside for a chat.
The victim followed them to a stairwell where they searched him, punched him in the face and were then joined by a number of other youhts who joined in the assault.
Det Con Ben Stone said: “The first offence happened in a very public place and I am sure people who were in the town would have seen either the robbery or the chase that followed.
“The victim has stated that a member of the public came to help him after the second offence and I would appeal to this person to come forward and tell us what they saw.”
If you have information relating to these incidents you can contact DC Stone, at Luton Police Station, in confidence, on 01582 394471, or Bedfordshire Police on 101 Station,, or text information to 07786 200011.