The mysterious swarms of drones in New Jersey have sparked calls for a 'state of emergency' until answers are given about the thousands of bizarre sightings. Mayors in 21 towns across the state have now written a joint letter to New Jersey Gov Phil Murphy calling for statewide action. The FBI has admitted that it does not know who is behind the flying objects, while the US military insisted it is not responsible. The White House says it is 'closely' monitoring the situation.