A teenager is recovering from facial injuries and a bout of concussion after being assaulted at Murray Bridge High School.

The boy was taken to hospital after being hit by two other students on Wednesday afternoon.

Murray Mallee Superintendent Ian Parrott says the school and police acted swiftly to resolve the problem.

"I'm pleased to say DECS have been very cooperative with us. Police attended at the time and we've actually arrested two youths in connection with the assault and they've been bailed to appear in the youth court in Murray Bridge on the 31st of October."

There's been two other serious bullying incidents at northern suburbs schools.

A teenager was hospitalised after being assaulted while a boy, his sister and their friend have received death threats.

Their mum Sharon says she's frustrated by the lack of action by police.
 

"We've had the police at the school twice in one week with them being chased and threatened to be killed. My son's been assaulted, the girl's been assaulted, they were constantly ringing us, threatening to kill my 11 year old daughter."