Homeland Security Secretary Markwayne Mullin: This is not 'another 9/11’

We continue to track major breaking news tonight. All flights are grounded across the United States at this hour. This here is a live look at the flight board at Orlando International Airport, and you can see there is a whole lot of red right now. About 10,000 flights across the country are either delayed or canceled. The transportation secretary says this is all due to some sort of disruption in the communication system. Secretary of Homeland Security Mark Wayne Mullen just gave an update on the situation. Take a listen. As we investigate what caused this, you always got to assume that as many cyber attacks that take place, you make that assumption. But as of right now, that's not known. So we're going to continue to work. The first thing we want to do is make sure we restore the communications, we get all the flights on the ground, and then we get back normal operations. But we're going to continue to work to find out what the root of the cause is. Mullen also says President Trump has been fully briefed on the situation and is monitoring any developments.