Queensland's chief health officer Jeannette Young said the girl's infection was revealed late on Friday morning and she was eager to investigate details of the case.
"I don't have any information," the top doctor told reporters. "We'll get genome sequencing back late today or early tomorrow.
"She was at school in the last few days. We've asked the principal to advise all children in that school to be immediately picked up and taken home and to go into quarantine for the next 14 days."
Parents were seen lining up around the block to collect their children on Friday morning, with one parent telling reporters he had been "quickly notified" of the development by the school after first hearing it on the news.
The infected student has been at school "in the last few days", Queensland's chief health officer says.
"I've got three here at the moment," he said. "I'll whisk them home, get tested I guess and we'll go into isolation for the next 14 days.
"They're excited they'll miss the last week of school - and equally disappointed they'll miss the first week of holidays."
When asked what he would do to pass the lengthy isolation period, he joked: "We'll stand around the piano all day ... just wish one of us could play it."
The new infection is so far not linked to an infected truck driver from New South Wales who visited several venues in Brisbane. That case was revealed last week.
Authorities believe the driver, who is in his 20s and partially vaccinated, was infected with the highly infectious Delta variant as Queensland continues to prevent new clusters from soaring into devastating outbreaks.
"He was infectious here in Queensland on Sunday, September 5, and Monday, September 6, and he went to a number of venues," Dr Young said.
Premier Annastacia Palaszczuk urged Queenslanders to get vaccinated as the threat of the virus persists in eastern states with soaring case numbers in both NSW and Victoria.
"This Delta virus is on our doorstep," she said.
"It is a clear and present danger. The best thing we can do as the state of Queensland is for as many people as possible to get vaccinated."
On Thursday, Palaszczuk confirmed a child from southeast Queensland had tested positive to Covid-19.
The 10-year-old boy is the brother of a 4-year-old who tested positive last week, linked to a Beenleigh childcare centre.
The Beenleigh cluster originated after the NSW truck driver spent time in the Logan/Beenleigh community while infectious.
The driver spread Covid-19 to a co-worker and her 4-year-old daughter, prompting hundreds of people linked to the childcare centre to go into isolation.
