Guojun Xuan, 65, and Silvia Zhang, 38, have been arrested for child endangerment after police found the children inside their £4 million California home. They were first called to reports of a two-month-old baby suffering a traumatic head injury, but also found 15 children aged up to the age of 13-year-old.

Investigators said surveillance footage revealed the nanny shook and struck the infant, and that the child wasn't taken to the hospital until two days later.

Organizations that track the material are reporting a surge in A.I. images and videos, which are threatening to overwhelm law enforcement.

One attorney called it “an incredible harm worthy of one of the largest verdicts in the history of the state.”

Former Australian of the Year Grace Tame has joined child safety advocates at a national government roundtable to address AI tools being used to create abuse material.

But, once police began to investigate, they found what one veteran officer described as a "unique case" with "unique challenges." Now, months later, several women who served as surrogate mothers for the couple are expressing shock that their babies are now in foster care,

Video showed the baby’s nanny shook and hit the child on May 5. He wasn’t taken to a hospital until two days later.

The majority of the kids were probably within the one- to three-year age range,” Arcadia Police Lt. Kollin Cieadlo tells PEOPLE