The remains of three children have been discovered in Tennessee after a person stumbled upon the remains in a wooded area of Memphis.

A woman was walking her dog on March 8 when she reported finding the skull of a human in Hickory Hill, which is in southwest Memphis, police said in a press conference.

Memphis Police Chief Cerelyn Davis said that officers located the skull near the woods’ edge and brought in dogs to search through the area. The dogs were able to find more human remains in a nearby drainage system on April 1. The search found 14 additional bones aside from the skull “consistent with human remains,” Davis added.

A medical examiner looked over the remains and determined that the bones belonged to three children between the ages of 3 and 7. “Our goal today is to conduct a thorough and methodical search of the area for additional evidence that will assist in identifying the deceased,” Davis added.

“We understand that this information is very difficult and deeply concerning to all of us. We want to reassure the public that there is no indication of any active threat at this time,” she continued. “Somebody knows where these children have come from. Someone knows the missing children that we have discovered in this area. It’s heartbreaking. It’s disturbing.”

There are around 170 people working on the case at the active crime scene, which includes some federal officials. Those who know anything about the case have been urged to contact the police.