A 16-year-old boy has been admitted to intensive care after being repeatedly stabbed.
The victim sustained wounds to his body and legs. Police were called to Landseer Road in Ipswich, Suffolk, just after 22:30 BST on Saturday.
The force said the boy remained in a "stable but serious condition". The offenders fled towards Nacton Road.
Three potential witnesses, who may have "vital" information, were urged to come forward.
Officers wanted to trace three teenage boys, described as white and aged between 14 and 16 years old, who were walking into town along Landseer Road from Nacton Road at the time.