K9 Unit
It meant that the K9 unit must be invited and they must start working as soon as they can. K9 is a unit with dogs that should smell the old clothes or anything similar from a missing person and get a scent. Then they will follow that scent and hopefully end the quest.
In other words, they will find the missing person. Most of the time these dogs are heavily trained and they can find the person. This meant that the dogs picked up the scent of the boy and they started to go crazy. They knew something. But what? Where are they going?