OKLAHOMA CITY (AP) — The Oklahoma City Police Department has placed officers on leave after reports of an April Fools’ Day prank that sent squad cars in pursuit of a baby being thrown out of a car before the call was revealed as a hoax.

Oklahoma City Police Capt. Valerie Littlejohn confirmed Monday that an internal investigation was ongoing but would not say how many officers were placed on administrative leave or provide details of the accusations.

“We are aware of a reported pursuit involving some of our officers that included serious claims, which has since been determined to be false,” Littlejohn said in a statement. “We take this situation seriously and are committed to ensuring a thorough review is conducted.”

The investigation followed published police radio audio from the night of April 1, reported by Oklahoma City television station KFOR and other stations, in which a dispatcher says that the “city just advised that the suspect threw a baby out the window.”

“The police officer that’s in pursuit does not have a radio. He’s just messaging his location,” the dispatcher says.

After a number of officers responded to the report, a dispatcher can later be heard saying: “It was an April Fools’ prank.”

Another dispatcher says: “Not funny.”

A message left Monday with the president of Oklahoma City police union president seeking comment on the incident was not immediately returned.

Oklahoma law makes it misdemeanor crime to report “knowingly false information which could result in the dispatch of emergency services from any public agency.” Punishment is a fine of up to $500 and an assessment for any costs associated with dispatching emergency personnel.