A 16-year-old boy has been arrested after a female teacher and two Year 11 students were stabbed at a western Sydney high school.
Paramedics were called to Bonnyrigg High School just before the bell rang at 9am on Thursday.
The teacher, 48, and two students, a 16-year-old boy and 15-year-old girl, have been treated by paramedics for stab wounds after they were reportedly stabbed with a metal ruler.
The school went into lockdown but just before 10am noted on its Facebook page that "classes have resumed as normal".
The teacher and boy were taken to Liverpool Hospital while the female student was taken to Westmead Hospital, NSW Police said.
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Their injuries are not believed to be life threatening.
Another 16-year-old boy was later arrested in a nearby car park.
A backpack was lying on the ground alongside a knife, a meat cleaver, a Stanley knife and some scissors. There was also a water bottle and a mobile phone.
The arrested boy has been taken to Fairfield police station.
As the new education year began this week principal Michael Bryce posted a video on the school's Facebook page saying Bonnyrigg High was "one of the best schools in NSW".
Police will hold a media conference at Fairfield at 11.30am.
The school caters to 1150 students.
A woman whose younger sister witnessed the stabbing told AAP her sibling was badly shaken by Thursday's incident.
The student rang her from the school to describe what had happened in the classroom.
"She just told me that someone in her roll call stabbed another kid and the teacher tried stopping it and (they) injured the teacher too," the woman said via Facebook.
