Travelers at Denver International Airport have been left stranded after a blizzard slammed the area today.

The airport was closed “until further notice” after the storm hit and it lost power for an hour this morning, reports The Denver Post. Officials also said that the weather made it impossible for planes to arrive or leave the airport. The FAA also barred flights from leaving due to low visibility.

According to FlightAware.com, which tracks flights nationwide, 636 flights departing Denver have been cancelled and 583 flights arriving there were also cancelled.

Reuters reports that the Denver area is expected to face 6 to 12 inches of snow today. The airport has also seen wind gusts up to 50 miles per hour. The storm has also caused school cancellations in Colorado.