All United Airlines flights in the US were grounded this morning for nearly an hour, over "dispatching information."

Though United hasn't indicated the cause for the grounding, tweets from onboard passengers and a news report have indicated various possible reasons.

"United began delaying flights at approximately 8 a.m. CT to ensure aircraft departed with proper dispatching information," United spokesman Charles Hobart wrote an in email to WIRED. "We resumed departures at about 8:40 CT and are accommodating our customers to their destinations."

Hobarth didn't explain what "dispatching information" meant, but passenger Edward Benson, the founder and CTO of the tech firm Cloudstitch, sent out a tweet indicating that his pilot had told passengers on his plane that they were being grounded due to a possible hack of United's computer network, which resulted in bogus flight plans popping up in the system.