NEW YORK – Hurricane Sandy grounded thousands of flights in the U.S. northeast Monday and upended travel plans across the globe, stranding passengers from Hong Kong to Europe. The massive storm threatens to bring a near halt to air travel for at least two days in a key region for both domestic and international flights.

Major carriers such as American Airlines, United and Delta cancelled all flights into and out of three area airports in New York, the nation's busiest airspace. According to the flight-tracking service FlightAware, nearly 10,000 flights had been canceled for Monday and Tuesday, almost all related to the storm.

The cancellations have already surpassed those from last year's damaging Hurricane Irene. They're now on par with a major winter storm in early 2011. Back then, 14,000 flights were scrapped over four days.