KANSAS CITY, Mo. -- Police said the remains of a baby boy were found buried in a shallow grave in the back yard of a house.

Thursday, investigators said a tipster told police that a 13-year-old girl had given birth recently and that the remains would be found behind the house near East 18th Terrace and Fremont Avenue.

"They did indeed find the remains of what appears to be a newborn child in the back yard," Capt. Rich Lockhart said. "The grave looked like it hadn't been there longer than a week or so, and the child was maybe 10 inches long."

Police said a 13-year-old girl lives at the house with her younger brother and sister, her mother and her mother's boyfriend.

"The 13-year-old gave birth to the child, and her and her mom buried the child in the back yard," Lockhart said.

Investigators said an autopsy showed the fetus was stillborn. The exact age of the baby is not known, however, police said it appears the girl was about five months pregnant.

The children were taken into protective custody. No names have been released.

No charges have been filed, but Lockhart said the case is still under investigation.

By state law, a 13-year-old cannot legally consent to having sex, so the father of the baby could face rape charges.

Police said the girl has not been cooperative about the identity of the baby's father and they may have to do DNA tests.

The teen's mother could face charges of child endangerment for failing to provide medical care for her daughter and possibly a misdemeanor in connection with the baby's burial, police said.

Neighbors said they were shocked by the case. Several said the 13-year-old girl and her siblings were rarely seen in the neighborhood.

"I've seen her, like, maybe three times since they've lived there. They don't come out and try to play with other kids or anything," neighbor Amber Moellenkamp said.

"I've never really seen them. I didn't even know there was any children there," neighbor MaryAnne Pittman said.