Delta Air Lines has grounded its flights due to a system outage - photo by Ted S. Warren / AP
Delta Air Lines has announced it has grounded all of its flights due to an outage to their computer system.

The airline tweeted on Twitter:

Due to a computer outage, flights awaiting departure are currently delayed. Flights enroute are operating normally.

Customers should check the status of their flight before heading to the airport while the issue is being addressed.

Delta News Hub on Twitter

to ground - to cancel and keep on the ground
outage - inability to go / work (usually electronic) 
enroute - on the way