A 15-year-old schoolboy was found left in the street with a head injury on Monday evening.
The boy was found injured on the ground in Fermor Crescent, opposite the junction of Carteret Road at around 6.30pm.
He was taken to the Luton and Dunstable Hospital and released after observations on Tuesday afternoon.
The officer in charge of this investigation, Det Con Gemma Widdowfield, is keen to trace anyone who can help piece together what happened to the teenager and how he sustained the injuries.
She said: “At the time the young man was found he appeared to be seriously injured, however, he has made a recovery and has since been released from hospital.
“It is still not clear how he came to be injured and I would appeal to anyone who saw the teenager last night to come forward and speak with the police.”
Anyone who has information relating to this incident is urged to contact police on 01582 473318, 101, text information to 07786 200011 or contact Crimestoppers on 0800 555 111.