Deputy Premier Steven Miles said all nine cases discovered on Saturday were connected to the Indooroopilly cluster.
It was the highest number of daily infections in almost 12 months.
The Indooroopilly cluster now numbers at least 18 people and Mr Miles implored more Queenslanders to seek virus testing.
"We did 11,468 tests in the last 24 hours. Our message is simple - that is not enough tests. We need more Queenslanders, particularly in the southeast, to get tested," Mr Miles told reporters.
He declared a "go hard, go early" response to the outbreak on Saturday after six new cases were linked to a high school student.
The local government areas of Brisbane, Ipswich, Logan City, Moreton Bay, Redlands, Sunshine Coast, Gold Coast, Noosa, Somerset, Lockyer Valley and Scenic Rim entered the harshest restrictions the sunshine state has seen at 4pm on Saturday.
The lockdown will last for at least three days.
Residents in affected areas can only leave home for essential work, study or child care, to exercise, buy food and supplies, and receive healthcare, including being tested for Covid-19 or vaccinated.
Non-essential travel must be within 10km of residences and everyone must wear a mask when outside their home.
All schools in the lockdown zone will be closed on Monday and Tuesday, while all staff and students of Indooroopilly High School and Ironside State School are in quarantine for two weeks.
Other schools affected by the outbreak include St Peters, Brisbane Girls Grammar School and Brisbane Boys Grammar School.
Chief Health Officer Jeanette Young suspects an infected medical student could be the index case of the outbreak and likely brought the virus into an Indooroopilly High School student's home.
• Exposure sites can be viewed at qld.gov.au/health/conditions/health-alerts/coronavirus-covid-19/current-status/contact-tracing
FOUR NEW CASES IN VICTORIA
Victoria has recorded four new locally acquired Covid-19 cases.
All are linked to the state's current outbreaks and all were in quarantine throughout their infectious period.
Health officials say Victoria administered 15,841 vaccine doses in the 24 hours to Saturday evening and processed 25,779 virus test results.
The numbers follow two cases reported on Saturday, one quarantined during their infectious period and the other a colleague of a Melbourne testing site worker at Moonee Valley Racecourse who was briefly in the community before isolating.
Health Minister Martin Foley said on Saturday the fellow traffic controller shared a lift after work with the first, whose diagnosis was confirmed this week.
"He (the second traffic controller) was isolated as soon as he was identified as close contact and didn't have much time in the community," he said.
He visited Devon Plaza shopping centre in Doncaster on July 28, so anyone there between 10.20 and 11.25 should isolate and get tested, he said.
Authorities were still investigating how the first Moonee Valley worker contracted the virus.
Initial results from genomic testing have linked the case to the outbreak at Maribyrnong's Ariele apartment complex sparked by a crew of NSW removalists.
However as of Saturday, no origin for the Frankston man's infection with the Delta strain had been established.
He visited his partner at a Newport apartment building while infectious and it is a close contact of this person who was the second positive case recorded on Saturday.
Victoria is living under relaxed restrictions since coming out of its fifth lockdown, but private gatherings are not yet permitted and strict mask-wearing applies.
