The cluster of coronavirus cases at a school in Sydney’s north-west has grown to 11, health authorities have confirmed.

The Tangara School for Girls in Cherrybrook is closed until August 24 while cleaning and contract tracing is under way.

NSW chief health officer Kerry Chant said of 14 new cases reported in the 24 hours to 8pm on Sunday, five were linked to the girls’ school.

A further two cases connected to the campus were reported on Monday, bringing the total to 11. They are seven students and four teachers.

The origin of the cluster remains under investigation.

Elsewhere, Bonnyrigg Heights Public School in western Sydney was also on Monday closed after a student tested positive to COVID-19.

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Last week, a student at the nearby Bonnyrigg High School tested positive for the coronavirus. The school was closed before reopening the day after on August 5.

The alert issued overnight on Sunday preceded confirmation of 14 new cases of COVID-19 in NSW in the 24 hours to 8pm on Sunday.

One new case is in hotel quarantine and one has no known source.

On Monday, Dr Chant encouraged NSW residents to avoid large gatherings, social mixing and excessive movement while the virus bubbles away.

St Agatha’s Catholic Church in Pennant Hills is also undergoing deep cleaning after a parishioner on August 5 and 6 tested positive to the virus, as is PharmaSave Pharmacy in Cherrybrook after an infected employee worked on August 6.

The worker, who wore a mask during their shift, was one of 10 new COVID-19 cases recorded on Sunday.

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NSW Premier Gladys Berejiklian has again urged people to “curtail their activity” as the state navigates a “critical phase” of the pandemic.

She hinted the state government might be forced to bring in tighter rules if warnings were not heeded.

“We ask people to curtail their activity. It’s very difficult [to contact trace] when people have attended a number of venues in one night,” she said.

NSW Health has also advised staff who had contact with a Hornsby Hospital healthcare employee to self-isolate for 14 days after the staffer worked in the emergency department on August 6 from 11am to midnight while infectious.

The worker wore a mask at all times while in contact with patients and was asymptomatic at the time but became unwell after their shift.

-with AAP