Local police confirmed that 13 people died as tornadoes swept across three counties in Indiana.
Twelve more died in Kentucky, with two fatalities in Ohio. Earlier, tornadoes hit Alabama, causing widespread damage.
“We are no match for Mother Nature at her worst,” said Indiana Governor Mitch Daniels.
He is due to vist affected areas on Saturday.
The storms – stretched across a vast part of the US Midwest – came days after another system killed 13 people.
The first deaths on Friday were reported in Indiana, where the small town of Henryville was badly damaged.
Reports of extreme damage included a roof torn off a high school.
An official from Clark County sheriff’s department described the nearby town of Marysville, Indiana – located close to Henryville – as “completely gone”.
Jenn Helvering, 24, told the BBC she saw a storm cell cross the highway as she drove towards Henryville. She then came across wreckage, including an overturned tractor-trailer, alongside the road near the town.
Ms Helvering, who posted a series of images online said she saw “what seemed to be a funnel”, when driving between two storm cells.
“The weather was terrible. I suddenly saw a tornado coming towards me, I could see it swirling, then I saw one behind me. I was stuck in between two tornadoes – my dad directed me while I was driving between the two tornadoes. It was truly terrifying.”
In Salem, Indiana, a toddler was found injured in a field after tornadoes passed through, reports said before being take to a children’s hospital, where she was later identified.
A family of four were found dead in Washington County, Indiana, Sheriff Claude Combs told the Louisville Courier-Journal.
Meanwhile, in Henryville, authorities found a man dead inside his vehicle. It was the first confirmed death in Clark County.
“We’ve got total devastation in the north-central part of the county [and] widespread damage from the west to the east,” Clark County Sheriff Clark Adam told CNN.
Neighbouring Marysville was totally destroyed.
“Marysville is completely gone,” said Chuck Adams of Clark County Sheriff’s Department.
As Friday’s storms grew in intensity, the National Weather Service issued severe tornado warnings for a host of states.