Police say a 3-year old boxer named Tyson, attacked his owner's 9-month old son as he was holding himself up against the coffee table.
"Went immediately for the child's face and neck," said Detective Bill Veteran from the Freemont Police Department.
"I didn't think the dog was aggressive at all," said neighbor Karen Simpson.
Neighors say the family moved into a home in Fremont's Irvington District, about two months ago.
"He seems nice. He was outside just barking, playing around outside and that's it. Never got beyond the fence or anything," said neighbor Jessica Smith.
But police say just 17 days ago, they were called to the same house after Tyson reportedly bit another family member.
The injury was not serious enough to label Tyson a dangerous dog. That would have given police a reason to keep Tyson at the Tri-Valley Animal Shelter in Fremont where he was temporarily quarantined. Instead he was sent home.
"We later learned, after this incident, they had not been completely truthful with the police dept. They said, well, at that time the dog had shown some aggression to the child. We didn't tell you then because we didn't not want to get our dog back," said Veteran.
Police say that information could lead to a charge of child endangerment.
"To me it's unthinkable that you're going to keep a nine month old child, you know, a child that's in diapers in close proximity to a dog that has exhibited aggression in the past," said Veteran.
Police say its likely Tyson will be euthanized. Experts at the Tri-Valley Animal Shelter, where Tyson is under quarantine, say that before placing an animal with your child, you should have the animal's temperament evaluated. That can be done at most animal shelters.