The father of a six-year-old girl who was killed when a car driven by an 86-year-old woman reversed into her family at a Sunshine Coast shopping centre has paid tribute to his daughter as his "moon and back".

Emily Armstrong and her daughters Indie (L) and Lily were hit by the reversing car. ( Facebook: Emily Armstrong )

Indie Armstrong and her family were on a pedestrian crossing when the crash happened on Sunday afternoon.

A witness said two children were sent flying by the impact. Indie was taken to Nambour Hospital where she later died.

Her father Jason shared a photo of his little girl on his Facebook page overnight and received an outpouring of love from friends and family.

Jodie Alexander Platt wrote: "Your precious little sweetheart. There are no words to measure such heartbreaking devastation — I'm just so so sorry for your immeasurable loss and pain."

Carolyn Stevens wrote: "We're all in shock over here. So so sorry Jason and Emily, our thoughts and prayers are with you all xoxox."

The girl's parents live in Yandina, near Nambour, and run the North Buderim Butchery shop, where flowers have been laid this morning.

Nambour resident Jeff Prince, who left flowers at the butchery, said he was devastated by what happened.

"We come here — this is our local shop," Mr Prince said.

"We just paid our condolences and bought some flowers for the family … just showing our local support.

Children leave messages of love and support for Indie Armstrong's family at a makeshift memorial. ( ABC News: ABC Sunshine Coast Nicole Hegarty )

"It's just a pure tragedy — kids have got their whole future ahead of them and they don't ask, they don't pray for any of this sort of stuff — they're just innocent out there in the public."

North Arm State School principal Kelly Edgar said in a statement support was being offered to students and staff.

"North Arm State School community is deeply shocked and saddened by the death of one of our Year 1 students, Indie Armstrong," she said.

"Indie was an enthusiastic, loving, friendly young girl who will be greatly missed by the North Arm State School community.

A message left on a noticeboard at the makeshift shrine to Indie Armstrong. ( ABC Sunshine Coast: Megan Kinninment )

"Our thoughts and sincere sympathies go out to the family, caregivers, friends and loved ones during this difficult time.

"Support is being provided to students and staff, and guidance counsellors will remain at the school to provide support in any way they can and for as long as it is needed."

Premier Annastacia Palasczuk described the incident as an "absolute tragedy".

"The condolences of all Queenslanders go with her family — they must be going through an incredibly traumatic and emotional time," she said.

Ms Palaszczuk said there were measures in place to ensure older drivers were fit to get behind the wheel.

"There is regular testing that's involved [with] elderly drivers over 75; they have to make sure their medical practitioner says that they are fit to drive," she said.

Grandmother, eight-year-old sister in hospital

Indie's 57-year-old grandmother, who was also hit by the car, is in intensive care at the Sunshine Coast University Hospital in a serious but stable condition.

Indie's eight-year-old sister Lily suffered non-life-threatening leg injuries but remains in hospital in a stable condition.

The girls' mother also suffered minor injuries.

The 86-year-old driver was not injured.

Six-year-old Indie Armstrong was taken to Nambour Hospital where she died. ( Supplied: Gofundme )

Police said there were many witnesses to the accident and that they also had CCTV footage of the crash.

Forensic crash unit officers plan to interview the driver later this week before deciding whether she will be charged.

Police Senior Sergeant Matt Campbell said the incident was being investigated by the Forensic Crash Unit.

"It's still very early days in the investigation but what I can tell you is that there is an 86-year-old female driver that is assisting us in our inquiries," he said.

The silver hatchback that police say reversed into a mother and her two daughters. ( ABC News )

Call for donations to help family

A fundraiser launched for the Armstrong family through GoFundMe had raised $35,800 by Monday afternoon.

The woman behind the fundraiser, Caitlin Fraser, said the Yandina family "really just need some time to grieve and get through this extremely hard and heartbreaking time ahead of them".

"Their eldest Lily has suffered leg injuries and is in hospital currently getting treatment," she wrote.

"Grandmother Sandy was also critically injured and is currently undertaking numerous surgical procedures.

"They are small business owners on the Sunshine Coast and really just need some time to grieve and get through this extremely hard and heartbreaking time ahead of them.

"With a funeral to organise and medical expenses for the other family members any donations would be greatly appreciated and would allow this family the time to grieve their beautiful daughter and help with expenses during this time."

A woman leaves her thoughts at a makeshift memorial for Indie Armstrong. ( ABC News: Megan Kinninment )

'Heartbeat of the community'

On Sunday night, dozens of Nambour residents gathered at a nearby park for a candlelight vigil to mourn the young girl.

The Shack Community Centre (SCC) in Nambour has also offered its services to anyone who feels they need support following the girl's death.

SCC Pastor Dale Dowler said there were "hearts broken" across Nambour, but the support shown for this family — who many didn't know personally — shows the "heartbeat of the community".

"They want people to feel loved and cared for," Pastor Dowler said.

Flowers have been left outside the North Buderim Butchery this morning. ( ABC News: Owen Jacques )

He said people at the vigil prayed not just for Indie and her family but also the woman who was behind the wheel.

Pastor Dowler said he hoped the community support provided some small comfort for the families.

"As a dad, I don't know how you come back from this, but to know that you have people around you who know you and love you, but also others who don't know you but love you, it must be very comforting," Pastor Dowler said.

A parent at the North Arm Primary school, Sharon Whiteman, said the local school community was shocked.

"There is just no winners in the situation our hearts go out to Emily and Jason and their families," Ms Whiteman said.

"The grandmother is unwell and hopefully recovering, and Lily with a broken leg.

Police talk to witnesses at the Nambour carpark where the accident happened. ( ABC News )

"There's obviously a big thread in the North Arm parents and carers group of people offering support and shock and expressing themselves."

Ms Whiteman said there would be a morning tea at the school this morning "for anyone who needs to talk and debrief with each other at 9:00am after drop-off".

"There's other families that have started a fundraiser because they're [the Armstrong family] small business owners and are obviously going to need some time to only focus on their families," she said.

"I think it's times like this that the community makes a big difference."

The Nambour Alliance business group also paid tribute to the family on Facebook.

"The Nambour Alliance, on behalf of the board, staff and members, extend our heartfelt sympathies to Jas, Emily and Lily Armstrong of Yandina, their extended family, friends and the Yandina community as they come to terms with the loss of little Indie in Nambour today.