Teen charged over NSW school stabbing

A 13-year-old boy has been charged over the classroom stabbing of a school student on the NSW south coast.

Police and ambulance crews were called to Shoalhaven High School at Nowra shortly after midday on Monday, where they found an injured 14-year-old student.

He was taken to Shoalhaven Hospital with a punctured lung caused by a stab wound to the chest before being transferred to the Sydney Children's Hospital at Randwick.

The boy remains in a serious condition, but his injuries are not considered life-threatening.

Shoalhaven detectives have been told he was involved in an argument with another student before being assaulted.

Inspector John Behrendt told AAP it was believed the attack took place in one of the school's classrooms.

A 14-year-old boy was arrested at the scene and taken to Nowra Police Station but released without charge.

A 13-year-old boy was taken into custody a short time later after attending Nowra Police Station with his mother, and has since been charged with wounding with intent to cause grievous bodily harm.

He's been bail refused to appear at a children's court on Tuesday.