TUCSON, AZ — Investigators in Tucson are looking into a disturbing discovery Tuesday of what members of the Veterans on Patrol group thought was a typical encampment, but may be a holding area for children sold as sex slaves.

Solar lights at an area near Interstate 19 and Valencia Road caught the attention of the veterans, who scour places where homeless veterans might be as part of their mission to get them off the street. Instead, they found trees that had restraints on them, a baby crib and stroller, hair dye, an outdoor bathroom and pornographic material. Also at the site was an underground cave about 5 feet tall that had a dresser and crates — large enough for a child to fit inside.

They did not find anyone at the site, but former Navy SEAL Craig Sawyer, who is filming "Contraland," a documentary exploring child sex trafficking, told television station KOLD it looked like someone had been there about 10 days earlier. "I didn't expect to see something this heinous and inhumane this close," Sawyer said. "I served in the military to keep things like this from happening here that's why I risked my security, so nobody here would have to put up with this." (Get Tucson Patch's real-time news alerts and free morning newsletters. Like us on Facebook. Also, download the free Patch iPhone app or free Patch Android app.)

The advocacy group notified Sawyer after finding the encampment, KGUN-TV reported. "And we are right there and our city is right there, our children are right there and it's not my problem if it's not in my backyard," Lewis Arthur, who was with the group looking for homeless veterans told KOLD. "Now it's in our backyard."

Sawyer told KOLD that as part of his research into the problem of child sex trafficking, he's "heard of rooms full of kids in houses and basements and things like that, but nothing underground like this."

"An underground cell, that's pretty creepy," Sawyer said, adding he saw another nearby site where "they are already digging with fresh tools and fresh dirt."

Sawyer founded Veterans For Child Rescue in 2017 and has dedicated his life to raising awareness about child sex slavery, rescuing victims and putting child sex traffickers behind bars. Working with other veterans and police departments, he uses his military experience to run covert operations across the country, according to the organization's website. Tucson police did not immediately comment, but were at the site taking photographs, KOLD reported.