American Airlines is grounding flights nationwide until 4 p.m. following a computer problem Tuesday afternoon, the Associated Press reports.
According to Twitter, the airline can't access their reservation and booking system.
Flights into American's five biggest cities -- New York, Dallas, Los Angeles, Chicago and Miami -- are stopped until 4:30 p.m., according to Fox News.
American Eagle flights, American's regional affiliate, heading to Dallas, Chicago or New York's LaGuardia Airport were stopped until 2:30 p.m.
Thousands of frustrated passengers reported being stuck on planes on runways unable to take off or landed, but were unable to get to a gate, the New York Times says.
About a dozen American flights at Minneapolis-St. Paul International Airport have been canceled, but passengers can't rebook until the reservations system is fixed.