The heartbroken father of a little girl killed in a Queensland shopping centre carpark has posted a beautiful tribute to his smiling daughter just hours after her tragic death.

Indie Armstrong, aged six, was waiting to cross the road with her mother and sister Lily, eight, when they were struck by a silver Subaru outside Nambour Shopping Centre on the Sunshine Coast about midday yesterday.

9NEWS understands the 86-year-old woman was reversing out of a parking spot, but for an unknown reason didn't stop.

Yandina girl Indie Armstrong was struck and killed in the accident. Picture: Supplied (Facebook)

While their 37-year-old mother escaped unscathed, the girls were seriously injured.

Indie was taken to Nambour Hospital with critical injuries and later died, while Lily remains in the Sunshine Coast University Hospital with non-life threatening leg injuries.

Friends and family have left tributes to Indie below her father Jason Armstrong's touching Facebook post, who described her as his "moon and back".

A vigil was held for Indie near the site of the crash last night. Picture: 9NEWS (Nine)

Families from across the Sunshine Coast gathered to pay their respects to Indie. Picture: 9NEWS (Nine)

Heartwarming messages were left for Indie at the vigil last night. Picture: 9NEWS (Nine)

"There are no words to measure such heartbreaking devastation... I'm just so so sorry for your immeasurable loss and pain," Jodie Alexander-Platt wrote.

"We can’t even begin to imagine what you are all going through Jason," Julie Rhodes wrote. "My boys love Indie, her sweet smile always lit up the room."

A vigil was held in honour Indie near the site of the crash last night.

A crowdfunding page has been set up to support Indie's family with various medical and funeral expenses.

The incident unfolded outside Nambour Shopping Centre around midday today. (9NEWS) (9NEWS)

The 86-year-old driver avoided injury. (9NEWS) (9NEWS)

The page said the girl's grandmother Sandy was also left critically injured and is now undergoing a number of surgical procedures.

The page has described Indie's parents as "small business owners".

"They…really just need some time to grieve and get through this extremely hard and heartbreaking time ahead of them," the page reads.

One campaign supporter has described Indie as a "very beautiful little girl".

Investigations are ongoing, with charges yet to be laid. (9NEWS) (9NEWS)

"Our house and our daughter who started prep this year in which Indi (sic) befriended her is heartbroken for Indi and her whole family," she wrote.

Ryan Hansen posted a touching message on behalf of the paramedics on the Sunshine Coast.

"As the paramedic crew who worked on Indie and her family before transporting her to hospital we saw first hand how distressing it was for the family so I'm hoping the money raised through this goes some way to providing comfort in these difficult times," Mr Hansen said.

Already the campaign has raised $5000 of a total goal of $20,000.

Shocked onlookers at the scene of the accident described the chaos as a huddle of emergency service workers started CPR on Indie.

Onlookers described the horrific scenes outside the shopping centre. (9NEWS) (9NEWS)

“All you could hear was (the mother) crying and saying, ‘my babies, my babies’,” a witness told 9NEWS.

Investigations are ongoing with charges a possibility. A report will be prepared for the Coroner.