Storms Kill 15 in Texas, Oklahoma, Kentucky and Arkansas

Powerful storms and possible tornadoes pummeled parts of Texas, Kentucky, Oklahoma and Arkansas on Saturday night, killing at least 15 people, damaging homes and leaving hundreds of thousands without power.

The severe weather, including the threat of tornadoes, was moving east on Sunday. More than six million people were under a tornado watch through Sunday afternoon, including parts of Indiana, Kentucky and Tennessee. More than 18 million people were in a wider area with an “enhanced” risk of severe weather.

In northern Texas on Saturday, a tornado left at least seven dead — including two children ages 2 and 5 — and close to 100 people injured, Gov. Greg Abbott of Texas said at a news briefing Sunday evening.

Three of those people were trapped in debris at a home, officials said. Another person died after his home was blown away.

The storm destroyed 200 structures or homes and damaged about 120 more, Mr. Abbott said.

In Oklahoma, two people were killed in the city of Pryor, northeast of Tulsa, as a result of overnight storms, the Oklahoma Department of Emergency Management said on Sunday.

In Arkansas, one person died in Benton County and multiple people were injured, according to the local authorities, who said in a briefing on Sunday that the area had likely been hit by tornadoes.

A woman died in a house in Boone County, Ark., according to city officials in Harrison, Ark. A 73-year-old woman was found dead yards from where her mobile home had stood in Baxter County, Ark., the sheriff’s office said on Facebook. Two people were killed in Marion County, according to the sheriff’s office there.

The storm also left one person dead in Louisville, Ky., Mayor Craig Greenberg of Louisville said on social media.

At Lake Ray Roberts Marina in Denton County, Texas, north of Dallas, a tornado damaged boats, boat houses and a fuel dock, and overturned several recreational vehicles on Saturday.

“There is so much damage, we don’t even know where to start,” the marina said on Facebook on Sunday, noting there were no serious injuries.

Melissa and Derek Collister, who fled their house Saturday night in Valley View, Texas, just north of Denton, said their house had a damaged roof and part of the ceiling in the bathroom had caved in.

As they drove around the neighborhood on Sunday, they saw houses that were severely damaged.

“It’s from end to end,” she said. “It’s not like it went straight through the middle or anything. It’s all over.”

Rosa Perez, 48, and her husband recently moved into a house in Valley View that they have been building for six years. As the storm passed, they could feel the house moving as if it would take flight at any moment. Now her neighbor’s mobile home sits a few feet from one of their walls.

“It was rocking and hitting our house,” she said. “I’m just glad our house was there because otherwise theirs probably would have blown over.”

In Rogers County, Okla., trees and power lines were knocked down by a possible tornado, cutting off electricity and leaving some roads inaccessible, the authorities said on social media.

Power was out in Claremore, a city about 30 miles northeast of Tulsa, and would remain so “for an extended period of time,” according to the city’s police department.

As of midday Sunday in Claremore, there were 23 storm-related injuries reported. Nineteen people were taken to hospitals, three of them with possible life-threatening injuries.

“The areas of town southeast of downtown Claremore are pretty devastated,” said Billy Tomlinson, 40, a lawyer in Claremore. “Massive old trees are uprooted everywhere, others snapped like toothpicks, fallen power lines all over.”

In all, more than 440,000 customers were without power in Arkansas, Kansas, Missouri, Kentucky and Texas on Sunday afternoon, according to the site PowerOutage.us, which tracks utilities information across the country.

The United States has come under an onslaught of destructive storms in the past week, with at least a few reports of tornadoes each day.

Five people died and part of a city was obliterated in Iowa on Tuesday after the southwestern part of the state was swallowed by a system that produced a powerful tornado that carved a 43-mile path and packed winds of at least 185 miles per hour.

Kristi Eaton and Mary Beth Gahan contributed reporting.