Parents are well-advised not to allow their children to connect to the network unlocked.
There are far too many worms and viruses out in the wild, and despite the claims in the commercials, firewalls don’t block and eliminate them all.
One minute, your son or daughter is sitting there, researching a school project. The next minute, they’re staring blankly and reciting a ransom note.
Fifty thousand dollars by midnight, and they’ll restore your child’s personality.
I agree with them: don’t call the police.
Just disconnect from the net and restore from backup.
(You do make backups of your kids, right?)