Thunderstorms ripped across Oklahoma prairies Thursday night as severe weather was expected to intensify Friday and bring the threat of powerful tornadoes to multiple states in the nation's heartland.

Powerful storms were forming Friday afternoon from North Texas all the way to Michigan, where a tornado warning was issued southwest of Kalamazoo. There were no immediate reports of any tornado on the ground.

In an eerie scene captured on video Thursday, a first responder drove straight at a storm near the western Oklahoma town of Fairview, where flashes of lightning illuminated a giant funnel that appeared to reach the ground. That storm, among the first outbreaks of severe weather on the verge of the spring storm season, was filmed by a camera mounted on the deputy's car.

Nearby, a 47-year-old woman and her 13-year-old daughter from Fairview were found dead in a vehicle near an intersection of a highway and a county road at about 10 p.m. Thursday, authorities said. The crash “appears to be tornado related,” Sarah Stewart, a spokesperson for the Oklahoma Highway Patrol, said in a statement.

“Severe weather struck Major County last night and tragically claimed the lives of a mother and daughter," Oklahoma Gov. Kevin Stitt said in a statement Friday. "I am praying for the family as they grieve this tragic loss, as well as all those impacted by the storms.”

The National Weather Service in Norman, Oklahoma, planned to send out a damage survey crew Friday to see whether Thursday night’s storms were confirmed tornadoes, meteorologist Ryan Bunker said. “As of right now, we’re still investigating that.”

Storms could be even more intense Friday, as more than 7 million Americans are at the highest risk of severe weather in an area that includes the metropolitan areas of Kansas City, Missouri; Tulsa, Oklahoma; and Omaha, Nebraska, according to the national Storm Prediction Center. Nearly 25 million people are at a slightly lesser risk in a zone that includes Dallas, Oklahoma City, and Milwaukee, Wisconsin.

Severe, scattered thunderstorms are expected Friday afternoon and evening from areas of the Plains states to the Ozarks and Midwest, the National Weather Service said.

“The greatest potential for a few strong tornadoes and very large hail should exist across eastern portions of Oklahoma/Kansas/Nebraska into western Arkansas/Missouri and southern Iowa,” it said.

The general setup for the strong storms is a clash between warm air streaming north from the Gulf Coast and cooler Canadian air behind cold fronts, according to meteorologists with the private forecasting service AccuWeather.

“This is probably our first real event this season where people are really starting to pay attention getting into the spring storm season,” said Melissa Mayes, deputy director of the Washington County Emergency Management Agency in Bartlesville, Oklahoma, north of Tulsa.

The spring storms in the forecast come near the start of what many call tornado season, which generally begins at different times in different parts of the U.S. Experts recommend a few simple safety steps to take before tornadoes hit, including having a weather radio and a plan for where to take shelter.

Meanwhile, parts of the Northeast were under winter weather advisories as rain, snow and slush made for a messy morning commute from Pennsylvania to Maine on Friday. Several vehicle slide-offs were also reported on the Maine Turnpike as drivers contended with sleet and snow.

Some schools canceled or delayed classes in states including New Hampshire and Maine.

The weather began to ease at midmorning in some areas, but Maine, Massachusetts, Rhode Island and Connecticut remained under weather advisories. In Ohio, flood warnings were issued in the southern part of the state.

In parts of the southern U.S., the weather pattern is also expected to usher in extremely warm temperatures for this time of year by the weekend.

“Temperatures will be 20-30 degrees above average, with 80s reaching as far north as parts of the Ohio Valley and Mid-Atlantic,” federal forecasters wrote in their long-range forecast discussion. “Daily records could become widespread.”

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McCormack reported from Concord, New Hampshire, and Martin reported from Atlanta. Associated Press Writer Patrick Whittle in Portland, Maine, contributed.