A Queensland boy is fighting for life after being hit by a falling tree not far from where a young mum was forced to use her body to save her baby from a devastating hailstorm.

The boy was trapped beneath a large tree that fell on him on Friday in storm-ravaged Coolabunia, one of the South Burnett communities hit hard by a line of super-cell storms and tornadoes on Thursday.

Two four-wheel drives were needed to get the tree off the boy, who has since been airlifted to the Queensland Children's Hospital in Brisbane in a critical condition.

"(He had) significant injuries, including head, chest abdominal and lower limb injuries," Senior Ambulance Operations Supervisor for the Darling Downs Stephen Johns said.

People caught up in the tempest have expressed shock at the ferocity of the winds and the scale of damage done by hailstones that were as big as tennis balls in some places.

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Young mum Fiona Simpson believes her four-month-old daughter could have died in their car had she not used her own body to shield the baby when huge hail broke their windscreen while leaving Nanango on Thursday.

"I looked down and I could see she was screaming but I couldn't even hear her, that's how loud it was," she told the ABC, adding the hail struck with such force that it "shredded" her grandmother's skin.

Ms Simpson and her grandmother suffered cuts and severe bruising but her baby escaped with just some bumps to her head.

Authorities expect the damage bill from Thursday's wild weather to be hefty, with crops wiped out, roofs torn from homes and the power network hit.

Severe Thunderstorm currently south of #Emerald. Destructive Wind Gusts, Very Large Hail and Heavy Rainfall. Find our warnings at https://t.co/wkXbkaARId. pic.twitter.com/t7fffOtEWB — Bureau of Meteorology, Queensland (@BOM_Qld) October 12, 2018

Talks are underway to determine if the hard-hit South Burnett region should be declared a disaster zone, with entire crops lost at harvest time, and homes damaged.

At Blackwater, in central Queensland, winds gusted to 144km/h, a wind speed associated with a Category 2 cyclone.

Queensland Dairy Farmers president Brian Tessmann said the storm's fury at his Coolabunia farm was like nothing he'd ever seen, with winds tearing the roofs from his home and dairy.

He said it was nothing short of bedlam as his house lost its roof, forcing him to hold doors shut as he watched debris swirl around inside its walls.

A chicken farm at Tansey saw 800 birds killed by hail, while a number of horses and other livestock were injured at multiple properties.

Authorities say wheat, barley, melon and fruit crops have been lost.

Stone-fruit farmer Shane Francis says his farm lost peaches and nectarines worth $2 million in 20 minutes of fury. They are not insured and also lost part of their crop to similar storms on Boxing Day last year.

"It's a little bit tough copping two whacks," Mr Francis told AAP.

State Opposition Leader Deb Frecklington said many farmers in her electorate of Nanango have suffered enormous losses.

"People will lose their jobs today because there is no fruit left to pick," she told AAP.

About 1000 insurance claims for storm damage have already been lodged.