Manus provincial police commander, Chief Inspector David Yapu, said the deceased, from Butjou in Pobuma LLG, was walking home after school at Manus Training Centre when she was confronted by the suspect, who works in a Chinese shop.
She was stabbed with a small knife and sustained injuries to her head, left hand and left side.
She was rushed to the Lorengau General Hospital but died on arrival due to loss of blood.
Upon hearing of her death, her relatives gathered at the police station on Saturday and demanded the release of the suspect from the cell so that they could kill her.
Police put up strong resistance and prevented them from entering the station.
PPC Yapu told the relatives that it was a police case now as the suspect was arrested and will appear in court.
He urged the relatives to remain calm and not take the law into their hands, otherwise, they will be arrested and locked up as well.
The suspect, who is also 22 years old, has been charged with murder. The reason behind the stabbing is yet to be established.
Police remain vigilant as the situation on ground is still tense.