A 17-year-old Chinese exchange student who had been reported missing last week was rescued on Sunday after nearly freezing to death in a tent outside Salt Lake City. Authorities say Kai Zhuang was the victim of a cyber kidnapping.

He was found alone and "very cold and scared" in a snowy canyon northeast of the city on Sunday.

"The victim had no heat source inside the tent, only a heat blanket, a sleeping bag, limited food and water, and several phones that were presumed to be used to carry out the cyber kidnapping," the Riverdale Police Department said in a statement Sunday. "The victim only wanted to speak to his family to ensure they were safe and requested a warm cheeseburger, both of which were accomplished on the way back to Riverdale Police Department."

Riverdale Police say Zhuang end up in the canyon alone

Officials said the teen had run away from his home on Dec. 28 after cybercriminals convinced him his family in China was being threatened. His family told police they had paid a $80,000 ransom after Zhuang sent them a photo indicating he was being held against his will.

Police say they suspect the foreign exchange student was tricked into running away to force his family to pay ransom. The FBI and and Chinese Embassy are helping local investigators find the kidnappers.

"We believed the victim was isolating himself at the direction of the cyberkidnappers in a tent," police said.

'Very cold and scared':Missing exchange student from China found alive, possibly victim of cyberkidnapping

What is cyber kidnapping? How does cyber kidnapping work?

While Zhuang's case may have recently drawn international attention and may be the first time many are learning about cyber or virtual kidnapping but the Federal Bureau of Investigation said they've been aware of this type of crime for more than 20 years.

The FBI said that while virtual kidnapping could take multiple forms, at the root of it an extortion scheme.

Generally, the scam involves criminals calling someone and tricking them into paying a ransom to free a loved one that they're made to believe has been kidnapped and is being threatened.

“Unlike traditional abductions, virtual kidnappers have not actually kidnapped anyone. Instead, through deceptions and threats, they coerce victims to pay a quick ransom before the scheme falls apart,” according to the FBI's website.

The FBI said that while the scam was once limited to Mexico and Southwest border states, it has "evolved so that U.S. residents anywhere could be potential victims."

Between 2013 and 2015, agents in Los Angeles were tracking scheme calls that were being made to Spanish speakers from prisons in Mexico.

“In 2015, the calls started coming in English,” said FBI Los Angeles Special Agent Erik Arbuthnot, “and something else happened: The criminals were no longer targeting specific individuals, such as doctors or just Spanish speakers. Now they were choosing various cities and cold-calling hundreds of numbers until innocent people fell for the scheme.”

The scammers typically bribed guards into getting them cellphones and would then pick a target city, learn the area code and begin dialing numbers until they get to a number where someone picks up.

"When an unsuspecting person answered the phone, they would hear a female screaming, “Help me!” The screamer’s voice was likely a recording," the FBI said. "Instinctively, the victim might blurt out his or her child’s name: 'Mary, are you okay?'"

Then the scammers would tell the individual that they have "Mary" and they intend to harm her if they don't get the ransom.

Most of the time, the scam doesn't work, the FBI said. People either quickly catch on that it's a scam or see that their loved one is at home.

"This fraud only worked when people picked up the phone, they had a daughter, and she was not home,” Arbuthnot said. “But if you are making hundreds of calls, the crime will eventually work.”

The scammers try to keep the person on the phone as long as possible to avoid them confirming where their loved one is and will typically ask for less than $2,000 to be wired to Mexico.

Growing cases of cyber scammers targeting exchange students

Zhuang's case is more sophisticated than the virtual kidnapping pioneered by inmates in Mexican prisons. Riverdale police explained that foreign exchange students, especially Chinese exchange students, have become a growing target of these virtual crimes.

Scammers contact the student and their family separately, persuade the student that their family is being threatened, and force them to take photos indicating they have been kidnapped. The cybercriminals then use those photos to trick the family into paying ransom, police said.

"The cyber kidnappers continue to extort the family by using fear, tactics, photos, and voice recordings of the victim, leading the family to believe the kidnappers are with the victim causing them harm," Riverdale police said.