In the United States, evacuation of passengers and staff at New York's JFK International Airport's terminal 8 was ordered after an unauthorised person entered a secured zone, through a door used by airline employees . Officials said the passengers were told to leave for rescreening. The rest of the airport was apparently unaffected by the incident.<br/><br/>The US airports are on high alert after a Nigerian man tried to blow up a Detroit-bound plane on Christmas Day.