A truck driver has been charged with drug driving over a horror Sunshine Coast crash which killed a toddler and left her baby sister seriously injured.

Police allege Alan Richard Knoblock, 52, from Rosemount, had illicit substances in his system at the time of the collision.

The crash happened in early January at Banya near Caloundra, when the truck ploughed into three vehicles across two intersections, leaving seven people injured.

Investigators allege the Mitsubishi Fuso first slammed into the rear of a silver Nissan Qashqai on Banya Av near Bruny St, forcing it into a fence, before continuing on and crashing into a blue Haval stopped in traffic at the intersection with Great Keppel Way.

Inside were sisters Ineza King, 3, and Itahe King, 1, travelling with their 37-year-old mother.

Three-year-old Ineza King was critically injured and airlifted to Queensland Children’s Hospital, where she died nearly a week later.

Her one-year-old sister was also seriously injured in the crash.

The crash sent shockwaves through the Sunshine Coast community as off-duty doctor Marcio Brussius Coelho recalled hearing the collision and racing to help, providing first aid to Ineza until an emergency helicopter arrived.

“Quite, I’d say, emotional as a father and having kids that age as well,” Coelho told 7NEWS after the crash.

“But at the moment, you just have to do what you need to as a doctor.”

A GoFundMe has been established for the King family, raising more than $25,000 as of Friday.

Knoblock has been charged with one count of driving a motor vehicle while a relevant drug is present.

It is a less serious offence than driving under the influence of drugs.

If found guilty, he faces a maximum penalty of three months in prison.

He is due to appear in Caloundra court later this month.

The forensic crash unit says investigations are ongoing.