Virginia police warned Thursday of what they said was an “abduction scam” in which parents are called by people who claim to have kidnapped their children.

Since May 4, Fairfax County police said in a statement, they have seen three reported cases in which a parent gets a phone call during the school day and hears a child crying or a child stating that they have been kidnapped. Then, a stranger gets on the phone and tells the parent their child has been abducted and demands ransom for the child’s return, telling the victim to wire the money to a specific location, police said. Information about the three reported cases was not immediately available.

Callers will try to keep parents on the phone so they cannot call the authorities, police said. They encouraged any parent who receives a ransom call about an abducted child to immediately verify their child’s location.

Many of these incidents go unreported, police said. Anyone who receives a call they believe to be phone scam may call police at 703-691-2131.