OKLAHOMA CITY >> A deadly storm system lashed a large swath of the southern U.S. with bands of sleet and snow for a third day today, grounding an additional 2,200 flights, leaving hundreds of thousands without power, forcing school closures and making already treacherous driving conditions worse.

Watches and warnings about wintry conditions were issued for an area stretching West Texas’ border with Mexico through Oklahoma, Arkansas and Louisiana, and into western Tennessee and northern Mississippi. Several rounds of mixed precipitation, including freezing rain and sleet, were in store for many areas throughout the day, meaning some places could get hit multiple times, forecasters said.

“It actually looks like it’s going to be getting worse again across Texas, it is already a pretty big area of freezing rain across western and southwestern Texas,” said Bob Oravec, a lead National Weather Service forecaster based in Camp Springs, Maryland.

Oravec said the icy weather is expected to move northeastward across parts of Oklahoma and Arkansas into western Tennessee and northern Mississippi before it starts to dissipate.

“By later in the day on Thursday it should be pretty much done, and all the … precipitation will be well downstream across parts of the South and where it will be mostly heavy rain,” Oravec said.

By late this morning, 2,200 U.S. flights had been canceled, including three-quarters of the flights at Dallas-Fort Worth International Airport and more than two-thirds at Dallas Love Field, according to the flight tracking service FlightAware.com. Dallas-Forth Worth International is American Airlines’ biggest hub, and Love Field is a major base for Southwest Airlines.

Many flights were also canceled at other airports, including in San Antonio, the Texas capital of Austin, and Nashville, Tennessee, compounding frustrations caused by the nearly 2,000 cancellations on Tuesday and roughly 1,100 on Monday.

Because of the storm, the Detroit Pistons were unable to fly home following their game Monday against the Dallas Mavericks, and the NBA postponed the Pistons’ home game tonight against the Washington Wizards.

Nearly 260,000 power outages were reported in Texas, including more than 130,000 in Austin, according to PowerOutage, a website that tracks utility reports.

Pablo Vegas, who heads the Electric Reliability Council of Texas, vowed that the state’s electrical grid and natural gas supply would be reliable and that there wouldn’t be a repeat of the February 2021 blackouts, when the grid was on the brink of total failure.

As the ice and sleet enveloped Memphis, Tennessee, Memphis-Shelby County Schools announced it would cancel classes today due to freezing rain and hazardous road conditions. The school system serves about 100,000 students. The National Civil Rights Museum in Memphis also closed due to the weather.

Also in Memphis, the icy weather delayed the funeral service for Tyre Nichols, who died following a brutal beating by police during a traffic stop. But more icy weather was moving in from the southwest just ahead of the funeral, which was pushed back a few hours to this afternoon.

“The third and FINAL round of freezing rain and/or sleet will start this afternoon,” the National Weather Service’s Memphis office posted on social media this morning. The leading edge of a wintry mix of precipitation was about 25 miles (40 kilometers) south of Memphis late this morning, radar showed.

The Dallas school district, which serves about 145,000 students, also canceled classes today.

Emergency responders rushed to hundreds of auto collisions across Texas on Tuesday and Republican Gov. Greg Abbott urged people not to drive. At least six people have died on slick Texas roads since Monday, including a triple fatality crash Tuesday near Brownfield, about 40 miles (64 kilometers) southwest of Lubbock.

Two Texas law officers, including a state trooper who was struck by a vehicle while investigating a crash on Interstate 45 southeast of Dallas, were seriously injured, authorities said.

In Arkansas, Republican Gov. Sarah Huckabee Sanders declared a state of emergency Tuesday because of icy conditions. Her declaration cited the “likelihood of numerous downed power lines” and said road conditions have created a backlog of deliveries by commercial drivers.