All flights in the United States have been grounded because of "extraordinary circumstances".
The Federal Aviation Administration (FAA) grounded all flights nationwide on Friday for "reasons of safety".
"Due to extraordinary circumstances and for reasons of safety. Attention all aircraft operators, by order of the Federal Aviation Command Center all airports are ground stopped. All departing traffic should remain grounded until further notice. Inbound international flights will be managed on a case by case basis," it said.
