Police did not know if the children were related or how they knew each other.
Four children aged 10 to 14 packed fishing rods in a parent's SUV, left a farewell note and drove more than 600 miles down the east coast of Australia before they were detained by police.
When the children were stopped near Grafton in the state of New South Wales, southeastern Australia, at 10:40 p.m. (8:40 a.m. ET) on Sunday, they locked the doors and refused to get out, New South Wales Acting Inspector Darren Williams told reporters Monday.
Police had to break into the car with a baton, he added.
"It's a long way, in excess of 600 miles from Rockhampton down to Grafton," Williams said. "I couldn't imagine one person actually driving all that way in two days."
The children were arrested, and Williams said they would be charged at a later date although he did not list the alleged offenses.
Officers have yet to interview the children — a 14-year-old boy, two 13-year-old boys and a 10-year-old girl — because they can't be questioned without a parent or guardian being present.
Police said they believe the group, which took with them fishing rods, cash and left a note at one of their homes, set off at around midnight on Saturday.
Police were not sure which child or children drove or why they left Rockhampton in the next-door state of Queensland.
Williams, who said they possibly shared the driving, did not say if the children were related or how they knew each other.