A Kingaroy mother thought her baby was going to die when they were pelted by hail after becoming trapped in her car during the supercell thunderstorms that wreaked havoc across Queensland's South Burnett region.

Key points: Fiona Simpson shielded her baby daughter from hail after it smashed car windows

Fiona Simpson shielded her baby daughter from hail after it smashed car windows She's been left with significant bruising after being pelted by hail

She's been left with significant bruising after being pelted by hail Her grandmother, also in the car, spent the night in hospital after being injured

Fiona Simpson, 23, was driving from Nanango on the D'Aguilar Highway to her home with her 78-year-old grandmother and 4-month-old daughter when the rain started to roll in.

Ms Simpson said she had not heard the warnings but knew she needed to pull her car over when the rain started getting heavy.

Mother Fiona Simpson, with her baby, was badly injured after being pelted by hail. ( Supplied )

"I wasn't driving very fast because I couldn't see very well… I couldn't see in front of me, I couldn't even see the line on the road."

She said the next thing she heard was a large bang.

"All this rain starts coming in, and the back window where my daughter was was just open ... it's gone," she said.

GRAPHIC WARNING: This story contains confronting images

"It was so scary but there was no time to be afraid … It just all happened so fast."

The quick-thinking mother leapt into the back of her car and acted as a human shield for her baby.

"I jumped over the back seat, over her car seat, holding my body over hers," she said.

"I looked down and I could see she was screaming but I couldn't even hear her, that's how loud it was."

Mother Fiona Simpson was badly injured after being pelted by hail. ( Supplied )

After another window smashed in the front of the car Ms Simpson moved to try and help her grandmother but both women were pelted with large hail stones.

Once the storm cell passed Ms Simpson drove her badly damaged car to a nearby home and screamed for help before the residents called an ambulance.

Ms Simpson said once paramedics arrived she went into shock and her whole body felt "numb".

SES crews have been called out to hundreds of incidents. ( ABC News: Bruce Atkinson )

"It wasn't until I got in the ambulance that I realised that if I didn't do that she [her baby] could have been seriously hurt or killed, anything could have happened," she said.

Her grandmother spent the night in Kingaroy hospital after most of the skin from her left arm was shredded while the other was left "completely black" from bruising.

Ms Simpson had significant bruising to most of her body but her daughter had small "bumps" on her.

Despite the terrifying ordeal the mother said she would not hesitate to do the same thing again.

Sorry, this video has expired Mobile phone footage of the wild storm.

"I'm just a mum — you do anything you can to protect your child no matter what, even at your own expense and I would do it again," she said.

"At the end of the day all that matters is that we're alive … a car can be replaced and bruises can heal and we're just all safe right now.

"If you know there is a storm coming just wait it out. We did the right thing, there's nothing else we could have done. I just can't believe hail could have done that."

Emergency Services Minister Craig Crawford said there had been more than 330 SES callouts overnight, with the number expected to climb throughout the day.

Widespread storms, destructive winds and large hail hit areas across the South Burnett to the Sunshine Coast with a tornado hitting Tansey, north-west of Murgon, shortly after 3pm.

Roofs were ripped from homes and sheds, orchards decimated and livestock took fright after the supercell storm tore through the area.

Close to 10,000 properties struck by the storm remain without power this morning.