At the auction, cameras and cell phones were not allowed inside the facilities, but we did manage to get audio of what was happening during the auction.

Over the weekend we went in undercover at a puppy mill auction in Thorp. This is a place where puppies and breeding dogs are bought and sold.

Before the auction started, protesters lined the street outside of the Horst Stables. Wearing bright orange t-shirts, protesters held signs hoping to spread the word of the inhumane treatment that happens in puppy mills.

Some protesters even went into the auction undercover, posing as bidders.

Inside we saw the animals in wire cages and pet carriers. Most of them were huddling together and trembling with fear.

The auction kicked off at 11:00 AM with the sale of leashes and other dog grooming supplies. Within a matter of minutes, the dog auction was bringing in thousands of dollars. Registered dogs were selling for a couple hundred dollars apiece, while unregistered dogs for less than fifty.

During the sales, protesters remained patient waiting for a signal to make their move.

Around 1:00 PM, the undercover protesters inside the building stood up, revealing their orange shirts, taking pictures, and chanting.

"No more puppy mills, No more puppy mills, No more puppy mills!"

As soon as the chanting started, some buyers turned violent. They began yelling, pushing, and kicking protestors. A 16 year-old girl we talked with says she was pulled to the ground by her hair.

While I was inside the auction watching protesters being pummeled to the ground, our photographer captured the chaos as it spilled out of the building. At this point we were no longer undercover.

Enraged people began yelling at us tell us we had to leave!

Despite the protest, the auction continued after some protesters and our cameras were escorted off of the property.

I tried to talk with some people who actually run puppy mills to get there side of the story, but they refused an interview with us.

Coming up on Monday night, we'll take a closer look at what happens to animals who have been rescued from puppy mills and we'll have a more in-depth look at how these dogs are treated behind closed doors.