A young girl was injured in a car crash on a Queensland highway that apparently left a gun and a cartridge case scattered on the road.

A man in his 30s suffered minor injuries when his Toyota pickup truck overturned on the Warrego Highway near Oakey about 9pm on Thursday, police said.

He was taken to Toowoomba Hospital.

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A police statement to 7NEWS.com.au did not confirm a report in the Toowoomba Chronicle that a four-year-old girl was also in the car at the time of the accident.

However, Queensland Ambulance Services said a female child had been taken to hospital in a stable condition.

Both she and the man suffered bruises and abrasions, according to QAS.

It is believed that no other vehicles were involved in the accident.

Officers have yet to question the man, but have already launched an investigation into the accident.

Numerous items were scattered on the street around the wreckage, including what appeared to be a black pistol, a gold-colored cartridge case, and pink-blue sunglasses.

The weapon was among the items that police seized as evidence.

The police did not provide any further information.