VANCOUVER -- Four teens have been arrested after a brawl turned violent sending one to hospital in serious condition earlier this month, say New Westminster police.

Charges of aggravated assault, robbery and assault with a weapon have now been laid against one of the teens.

The fight took place on Saturday, April 10 at about 8 p.m. on the grounds of Queensborough Middle School involving teens aged 15 to 18 from across Metro Vancouver, police say.

In a statement released Monday, police say the suspects were fleeing using public transit when they were arrested. The victim was located nearby with serious stab wounds, the department said. He is still in hospital but is expected to recover. Police say the motive for the stabbing and the fight is still unknown.

“Witness accounts, as well as video or any social media posts connected to this event are of interest to investigators,” stated Sgt. Sanjay Kumar

Police say the teens are known to them but stopped short of calling the incident gang related.

The New Westminster police major crime unit has taken over the case and say any witnesses who have any information to call police at 604-525-5411.