A SUDDEN lightning strike killed an eight-year-old girl as she climbed off a backyard swing just feet from her horrified relatives.

Her nurse mom desperately performed CPR on her own daughter, but the youngster could not be saved.

The freak tragedy unfolded at a family home in rural Serena, Illinois, on Friday, July 3.

Kinslee Tschida had been playing on the swing with her cousins when the family heard thunder rumbling nearby.

Her uncle immediately told the children to leave the yard and head inside the house, which was about 20 feet away.

Kinslee was getting down from the swing when lightning suddenly tore through the area.

“Kinslee was just climbing off, and all of a sudden, in an instant — I mean, there was no warning … It came right in between the tree,” her grandfather Chris Scheib told WGN-TV.

Scheib, who helped raise Kinslee, said the strike came just seconds before she would have reached safety.

“In 5 or 10 seconds, she would have been fine,” he told WLS.

Another of Scheib’s granddaughters was standing less than four feet from Kinslee but was not injured.

Other family members were also nearby and witnessed the devastating strike.

Kinslee’s mother and uncle immediately began CPR as they fought to keep her alive.

“They did try CPR. My son and my daughter – on her own daughter – and being a nurse, you know she took that real hard. She can’t save her own daughter,” Scheib said.

“Basically, there’s nothing else you could have done.”

Emergency crews rushed Kinslee from the home to OSF St. Elizabeth Hospital in Ottawa.

She was later pronounced dead from her injuries.

The La Salle County Coroner’s Office told The Post that an autopsy was carried out on Sunday.

Officials said a formal cause of death is expected to be determined within four to five weeks.

“It’s unfathomable, it’s unrealistic, it’s hard to grasp,” Scheib said.

Kinslee was due to begin third grade at Rutland Grade School this fall.

Her family remembered her as a joyful child who loved singing and dancing, WGN-TV reported.

A GoFundMe has been launched to help her relatives pay for medical and burial expenses.

“You try to muddle through it, I guess. I never had to deal with this in my life until now, and it’s changed me. I think we’re all broken,” Scheib said.

Kinslee is believed to be the fourth person killed by lightning in the US this year, according to the National Lightning Safety Council.