Investigators believe the disappearances are part of plot in which scammers instruct the Chinese students to go into hiding under threat that their relatives will be harmed.
Yue (Kandy) Liu, 17, was one of three Chinese nationals studying in Canada that police said went after becoming targets of a kidnapping scam.
The other two students were located over the weekend.
The families in China are then informed the student has been kidnapped and told to pay a large ransom.
Brister said the three students may have been targeted due to their recent arrival in the country.
Const. Jenifferjit Sidhu said Ke (Jaden) Xu, 16 was found Monday but did not have any further details.
"The students are somewhat isolated - they don't have a lot of friends or family here in Canada".
Juanwen Zhang, 20, was last seen Wednesday afternoon in the Yonge and Grenville streets area.
Police said they urged several of her friends to continue texting her. Zhang turned on her phone Saturday and saw messages from her friends and immediately got in touch with police.
Anyone with information regarding these scams is asked to contact police at 416-808-5200 or 416-808-4100 or Crime Stoppers anonymously at 416-222-TIPS (8477).
Ke "Jaden" Xu, 16, was last seen Thursday morning in the Eglinton and Midland avenues area.
He is described as six-feet, one-inch tall with a thin build. Xu was possibly wearing a red winter coat, grey trousers and a black backpack at the time of his disappearance.