A 15-year-old girl has been charged with wounding with intent to cause grievous bodily harm after the fight in which her schoolmate, also 15, was slashed on her face with a knife and stabbed on her chest and hand on Monday.
The fight happened outside the Williamsville Secondary School compound and was recorded and shared on social media.
The wounded girl was, up to Thursday, still being monitored at hospital.
Police said the alleged attacker, who was arrested on Tuesday, was also charged with possession of an offensive weapon.
She is expected to appear virtually before a San Fernando magistrate to face the charges on Friday.
The charges were laid by WPC Blackman of the Southern Division.