A state of emergency has been declared for one county in Tennessee after slow-moving thunderstorms spawned flash flooding across the region Wednesday.

The National Weather Service (NWS) office in Memphis issued a flash flood emergency midday after several inches of rain fell in a short amount of time - up to 10 inches in some locations.

“It’s been a hell of a day in Selmer, but we’re going to get through this,” Mayor John Smith told FOX13.

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McNairy County Mayor Larry Smith declared the state of emergency on Wednesday morning, and it remains in effect through Thursday.

Severe flash flooding was reported Wednesday in the town of Selmer, Tenn.

Severe flash flooding was reported Wednesday in the town of Selmer, Tenn. (McNairy County Sheriff's Office)

Flash flooding in Selmer put most of downtown under water, including roads, bridges and businesses.

Residents were encouraged to boil and conserve water.

The McNairy County Sheriff's Office said that the 911 center was flooded and needed to be "quickly evacuated due to excessive flooding."

Floodwaters overtook roads and left some vehicles stranded on Wednesday as drenching storms pounded northern Mississippi.

Floodwaters overtook roads and left some vehicles stranded on Wednesday as drenching storms pounded northern Mississippi. (Ecru Police Department)

Calls were rerouted to Hardin County as officials worked to move into a mobile command center by Wednesday night.

“We’ve had flooding before, but nothing that I can remember to this magnitude,” Smith told FOX13.

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In neighboring northern Mississippi, at least one person was rescued from a home in Ecru, nearly 30 miles north of Tupelo.

The town of Ecru Police Department said on Facebook that roadways across the town were covered by water.

Floodwaters overtook roads and left some vehicles stranded on Wednesday as drenching storms pounded northern Mississippi.

Floodwaters overtook roads and left some vehicles stranded on Wednesday as drenching storms pounded northern Mississippi. (Ecru Police Department)

Okolona resident Quineisha Judd shared a video on Facebook of Adams Street, which was under several inches of water Wednesday morning as storms hit the area.

Vehicles also were submerged in floodwaters.

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The NWS office in Memphis said that another warm and muggy day is in the forecast for Thursday, with scattered thunderstorms including some strong storms across northern Mississippi.

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Damaging winds and flash flooding were the main concern throughout the day.