A frightening viral challenge is scaring children and alarming police from Spain to South America and the United States.

Parents everywhere need to hear about this horrifying new form of cyber-bullying and how police are saying it even led a 12-year-old girl to take her own life.

The name of this “game” is Momo, and it originated on WhatsApp, a tool that offers free messaging and phone calls for people all over the world.

While this technology offers a wonderful way for family and friends to stay connected to one another, even when they are on different sides of the world, it can also pose a major threat when it comes to children’s safety on the web.

This is because WhatsApp is encrypted and can be used anonymously — meaning that parents and police will have a difficult time keeping track of messages sent from WhatsApp account and monitoring any potential criminal behavior.

Here is how the Momo cyber-bullying works: Kids are encouraged to send a message to a number on WhatsApp. Due to a combination of curiosity and peer pressure, kids send a message, then receive a message from “Momo” in return.

Along with a horrifying wide-mouthed, bug-eyed picture of Momo, they also start to get violent images and a series of increasingly dangerous dares from the anonymous bully. Children are told that they if they do not perform these tasks, they will be cursed or visited by Momo herself.

Eventually, these threats ratchet up to the kids being encouraged to commit suicide. Tragically, police in Buenos Aires say that a 12-year-old girl’s recent suicide seems to be linked to her recent online activity, specifically her participation in the WhatsApp “Momo” challenge.

Here’s a video about this frightening trend, shared on YouTube by Inside Edition:

Many are comparing the Momo challenge to the Slenderman, a horror character which originated on CreepyPasta and led two children to attempt to murder their friend, allegedly at the behest of Slenderman himself.

Although these stories might sound bizarre to adults, it is important to remember that children’s brains are not as developed as ours. Their prefrontal cortex is still being built, and research has shown that when this part of the brain is underdeveloped, it complicates our ability to be discerning and differentiate fact from fiction.

In short: an underdeveloped prefrontal cortex can mean increased gullibility. Add to this peer pressure and the fact that kids have wild imaginations and easily slip into the world of fantasy, and it is easy to understand how a scary picture and threatening messages can turn from a viral joke into a horrible real-life tragedy.

Law enforcement officials across the world are urging parents to talk to their kids about this dangerous game, and to make sure children know to never message strangers on the Internet, even if their friends are engaging in such behavior.

For more tips on talking to your kids about cyber safety, visit Kids Health.