A 15-year-old cyclist was left with a broken arm and chipped collar bone after a collision with a lorry on Monday.
The driver failed to stop after the collision at about 7pm at the junction of Crawley Green Road and Vauxhall Way.
The cyclist was trying to cross the road when the white flat bed lorry hit him.
PC Dave Charlton said: “This is a very busy road junction and I am sure that other motorists were about at the time of the collision and may be able to help piece together exactly how the collision happened.
“We also know that the lorry was being driven by a man and was also carrying a male passenger. I would urge anyone who can help to identify these men to come forward and assist with this investigation.”
Anyone with information relating to this incident is urged to contact PC Charlton at the Bedfordshire and Hertfordshire Roads Policing Unit on 101 or text information to 07786 200011.
Alternatively you can contact the independent crime fighting charity Crimestoppers, anonymously, on 0800 555 111.