A 17-year-old boy has been stabbed, and hit with a tree branch and a skateboard when five other male teens attacked him on Sydney's upper north shore.
The boy was waiting for a friend at a sports oval on Burraneer Avenue, St Ives, about 6pm on Saturday when one male hit him with the branch before another stabbed him twice in the shoulder, police say.
Another male struck him with the skateboard while a fourth male threw a metal object at him, causing the 17-year-old boy to drop his phone.
The group, all described as Caucasians, with one in his early to mid teens and the others in their mid to late teens, stole the phone and ran away.
The teenager was taken to Hornsby Hospital in a stable condition.
© AAP 2020