The investigation began with the search for a 12-year-old girl.
Her parents received a phone call from a foreign number with a person on the other line demanding a $1,000 ransom and claimed to have the child.
Local officers received help from an FBI task force.
That led investigators to a home on Johnson Street in Spring Valley where they found the girl, along with three other missing girls from Clarkstown.
All of them were said to be safe.
Police said none of them were being held against their will and they all knew each other.
On Monday, a woman at the house would not comment on what happened, but acknowledged some sort of mix-up.
Spring Valley police made no arrests and returned the other three girls to their police counterparts in Clarkstown, who then reunited the girls with their families.
The investigative focus now centers on the ransom call and who made such a serious threat that warranted the resources of the FBI.
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