Seven teenagers have suffered stab wounds after a brawl near a house on Sydney's lower north shore.

Police were called to a home on Mowbray Road at Chatswood shortly after midnight following reports of a disturbance between two groups.

Five teenage males, aged between 16 and 19, were stabbed during the fight and took themselves to Royal North Shore Hospital with non-life threatening injuries.

At the hospital, another fight broke out among the injured teens and police were called to break up the brawl.

Two other 17-year-old boys also suffered stab wounds and took themselves to St Vincent's Hospital.

Their injuries were also not considered life threatening.

Officers said some witnesses are not co-operating with police and a number of items were seized for forensic examination.