A father on the pick-up run who hit six children in the car park of a Queensland school on Wednesday is believed to have "touched the wrong pedal" while reversing.

In addition to hitting six schoolchildren, seriously injuring three, the 42-year-old hit two other cars and a wall when he "accidentally accelerated", according to police.

The scene at the Caboolture school was described as "chaos" by emergency services. Credit:Nine News

Emergency services were called to the Australian Christian College on Cottrill Road in Caboolture about 3.10pm, just as school had finished for the day.

"It was panic stations upon arrival, there was a lot of distressed students, a lot of distressed parents, no one knew what was going on, it was basically chaos," police officer Greg Price told Nine News.