No arrests have yet been made, 24 hours after a 17-year-old boy was stabbed in Preston city centre.
Lancashire Police said they have not identified any suspects in connection with the knife attack which happened at 4.45pm yesterday (Sunday April 7).
The force put out an urgent appeal for information following the 'targeted attack', which happened close to B&M Bargains in Carlisle Street.
Officers are appealing for information on three teenagers, thought to be aged between 15 and 18, who chased a 17-year-old boy before stabbing him in the back and stealing his bicycle.
The air ambulance attended the scene of the attack and airlifted the boy to Blackpool Victoria Hospital for emergency treatment.
North West Air Ambulance said his injuries are serious, but not considered life threatening.
Insp Chris Walsh from Preston Police said: “We think this was a targeted attack and that both the attackers and victim are known to each other.
“We have a number of officers working on tracing the offenders and arresting them.
“We know they have made off towards Church Street and the Avenham area following the incident.
Did you see three youths with a bike in this area? Perhaps you were driving in that direction and saw them?
If you have any information or potential dash cam footage we need you to get in touch.”
You can call police on 101 quoting incident number 1095 of Sunday, April 7 or email ForceControlRoom@lancashire.pnn.police.uk
Alternatively, independent charity Crimestoppers can be contacted anonymously on 0800 555111 or online at crimestoppers-uk.org.