The Federal Aviation Administration said early Wednesday

that there was no immediate estimate for the restoration of the NOTAM system.

Flights across the United States were grounded Wednesday morning

after the Federal Aviation Administration said it had ordered

All domestic departures to be delayed until 9 a.m. ET

to allow the agency to check safety information after experiencing a computer outage. The White House said there was no evidence the outage was the result of a cyberattack,

although President Joe Biden had instructed the Department of Transportation to do a "full investigation" into the cause.

About 3,704 flights within, to and out of the U.S. were delayed as of around 8:26 a.m. ET Wednesday,

according to the online flight tracker FlightAware. It added that 567 had been canceled.