A 17-year-old boy rang 999 to ask for an ambulance after he was stabbed in an alleyway near a high school.
Police said the teenager had called the emergency services himself at about 18:30 GMT on Monday.
Five people have been arrested in connection with the attack in Ipswich.
The boy was found in the alley between Bramford Lane and Broadway Lane, next to Westbourne Academy. Suffolk police said the grounds of the school would be searched as part of the investigation.
The victim was taken to hospital with a stab wound that is not thought to be life-threatening or life-changing.
Two boys, aged 16 and 17, two 18-year-old men and a 20-year-old man were arrested in connection with the the stabbing.
