(Reuters) – Hundreds of flights into and out of Chicago’s O’Hare and Midway airports were canceled on Sunday as a winter storm system dumped moderate to heavy snow on the Upper Midwest and Lower Great Lakes regions before heading toward the U.S. Northeast.

A winter storm warning was in effect in the Chicago area on Sunday afternoon, with total accumulations of up to 10 inches (25 cm) expected by midnight CST, the National Weather Service said.

It warned of difficult driving conditions in and around the country’s third-biggest metropolitan area, where snow began falling on Saturday afternoon.

As much as 13 inches of snow fell in parts of Michigan and up to 9 inches in parts of Minnesota by 8 a.m. CST on Sunday, according to the National Weather Service.

At O’Hare International Airport, the world’s fourth-busiest airport, United Air Lines and American Airlines have scratched most regional flights and some mainline service, while Southwest Air has canceled most flights out of Midway International on Sunday evening and Monday morning, the airports said.

Passengers took to Twitter to vent their frustrations over one of the first winter storms to snarl air traffic in the region this season.

“To all our fans in Vegas – we are stuck in Chicago from the snow storm, we are so so sorry. Winter weather is (sic) wrecked our plans. This sucks,” wrote the rock band One Republic in a Twitter post. The group had a show scheduled on Sunday night at the Hard Rock Hotel & Casino in Las Vegas, Nevada.

All told, more than 1,200 flights into and out of O’Hare were canceled as of Sunday afternoon, according to the Flightaware tracking service, while nearly 200 Midway flights were scratched.

At Detroit’s Metropolitan Wayne County Airport, a Delta flight arriving from Buffalo, New York, skidded off the runway and came to a stop on a grassy verge around midday on Sunday, but there were no injuries, local media reported.

Representatives of the airport and the airline could not be reached immediately to confirm the reports.

(Reporting By Frank McGurty; Editing by Alan Crosby)