 to keep people safe. Some experts say the situation at hospitals is dire. Mass General Brigham, for example, has canceled all non-critical visits, but the ER there in Boston remains open. Now, domestically, Delta, American, United, they're all affected, issuing ground stops early this morning. FlightAware says there are some 4,400 flights delayed into or out of the United States. That's Fox Business' Kelly Saberi reporting.