​​A four-day, once-in-a-generation weather event is pounding the middle of the U.S. with destructive tornadoes and life-threatening flooding.

Friday marks day three of the devastating storm. Here’s what you need to know:

7 deaths reported in 3 states

At least seven people have died across three states.

One death — a local fire chief — was confirmed in Missouri. Garry Moore, 68, who was the chief of the Whitewater Fire Protection District, died in the line of duty, possibly while helping a stranded motorist, according to the Missouri Highway Patrol.

Another death was confirmed in Hendricks County, Indiana, just outside of Indianapolis. A 27-year-old man was driving when he hit downed power lines in the road, and then he got out of his car “and came into contact with the live power lines,” the Hendricks County Sheriff’s Office said.

Another five weather-related fatalities were confirmed in Tennessee, according to state officials.

Gov. Bill Lee announced the fifth death in the state during a news conference Thursday evening, where he spoke of the “immense devastation” wrought by a powerful tornado that tore through the small city of Selmer, in the southwestern part of the state, between Memphis and Nashville.

Lee had declared a state of emergency in Tennessee, as did Kentucky Gov. Andy Beshear.

“We are facing one of the most serious weather events we’ve had forecast,” Beshear warned on social media. “Please stay alert, take all precautions, and be prepared.”

Tornado threat

Since the outbreak began Wednesday, there have been at least 42 reported tornadoes from Arkansas to Ohio. This includes an EF-3 tornado in Selmer, Tennessee, with winds of 160 mph, and an EF-3 tornado in Lake City, Arkansas, with winds of 150 mph.

Matt Ziegler documented the moment the tornado hit Lake City.

“I’ve always heard that they sound like a train on a track, but to be honest with you, it was eerily quiet,” he told ABC News. “If you weren’t looking, you wouldn’t know that there was a major tornado just a field over from us.”

On Friday, there’s another moderate risk for severe weather — including damaging tornadoes — from northeast Texas to Little Rock, Arkansas, to southern Missouri.

On Saturday, the severe threat is labeled “enhanced,” with the potential for strong tornadoes from Louisiana to Tennessee.

“We are facing one of the most serious weather events we’ve had forecast,” Beshear warned on social media. “Please stay alert, take all precautions, and be prepared.”

Flash flooding threat

Since Wednesday, over 6 inches of rain has inundated Tennessee and over 4 inches of rain has fallen in Arkansas and Kentucky — and the threat isn’t over.

A massive flood watch on Friday stretches from Texarkana, Texas, to Little Rock to Memphis to Nashville to Louisville, Kentucky, to Indianapolis to Columbus, Ohio, to Fort Wayne, Indiana.

Arkansas is in the bull’s-eye on Friday, with much of the state bracing for up to 10 inches of rain.

Another high risk for flash flooding is in effect Saturday from Arkansas to Kentucky.

By the time the storm ends, rain totals could be well over 15 inches. Some cities may see record-high four-day rain totals.

Rivers, creeks and other waterways could also advance into major flood stage from Arkansas to Kentucky.

The system will finally move east Sunday afternoon, bringing rain to the Southeast on Sunday, Monday and Tuesday.