The Yellowstone County Sheriff's Office says that a 12-year-old child in Lockwood was selected to take part in the MOMO Challenge.
According to a post on their Facebook page, the Sheriff's office took the call Monday evening.
The Sheriff's Office is asking parents to be aware of this very dangerous activity.
"Here is where your vigilance comes in. Don't trust unknown numbers. Change email passwords frequently. Block unknown numbers. Also, for your kids, do random audits on their phones. See what they are doing. Be a snoop in their phone. Let them know you will be doing these random audits. Tell then you love them. There are bad people out there. No phones or electronic devices in their bedroom when it's time for bed."
The Sheriff's Office explains how the MOMO Challenge works.
"Here is what the Momo Challenge is: People can access Momo through the Whatsapp of through Facebook. In order to meet Momo you will be given a series of tasks to complete. These tasks must be verified through pictures and/or video's taken. The tasks progressively become more violent and dangerous. The final task has been reported as being suicide or extreme violence."