A blizzard that has already cancelled or delayed thousands of airline flights and injured a passenger and crew member on a commercial jet over the Dallas area could dump nearly a foot more snow in some states, forecasters said on Thursday, Reuters reports.

Parts of the U.S. Midwest and Southeast were being hit with the first wave of heavy snow and rain expected in the central United States through the weekend, said Marc Chenard, a meteorologist with the National Weather Service.

“Through this morning there have already been amounts as high as 6 to 10 inches (of snow) across those areas and additional snowfall of 10 inches is possible throughout the day and tonight,” Chenard said. “Travel is going to be very difficult across the areas under weather and blizzard warnings.”

A passenger and a flight attendant suffered knee and back pain after an American Eagle flight operated by Mesa Airlines hit turbulence over the Dallas-Fort Worth area, American Airlines said in a statement.

Flight 5781, a Bombardier CRJ-900 aircraft that departed from San Luis Potosi International Airport in Mexico carrying 75 passengers and 4 crew members, was diverted to Austin, Texas.

The plane landed safely and the injured passenger and crew member were treated and released from a local hospital in Austin, the airline said.

In the Midwest, winter storm and blizzard warnings were in effect for parts of Kansas, Nebraska, North Dakota, South Dakota and Minnesota, the National Weather Service said.

The storm, which began late on Wednesday, contributed to the cancellation of more than 1,000 flights and delayed another 4,200. Nearly 400 flights to or from Dallas-Fort Worth International Airport were cancelled, with hundreds delayed.

Chenard said the storm system caused heavy rain and thunderstorms with the risk of flash floods in the southeastern United States, including parts of Texas, Louisiana, Mississippi and Alabama.

A tornado watch for parts of central and southwest Louisiana and southeast Texas were in effect on Thursday.

Kansas Governor Jeff Colyer on Wednesday declared a state of emergency. “We hope that travellers will be wise by paying attention to weather alerts and not unnecessarily placing themselves in harm’s way as the storm moves through,” Colyer said in a statement issued by his office.