Parents and students at Arthur Phillip High School have not been told about the arrest of a second teenager from the Parramatta school following the killing of a NSW Police employee on Friday afternoon.

Last week, Arthur Phillip pupil Farhad Jabar walked up behind NSW Police finance worker Curtis Cheng and shot him in the back of the head at point-blank range. 

On Wednesday, dawn raids by more than 200 police officers ended with the arrest of another 16-year-old Arthur Phillip student in Wentworthville, in Sydney's west, that has been raided twice in the past year.

Police believe that Jabar's 16-year-old classmate recruited him to an extremist circle that held lunchtime prayer groups and attended regular sessions at Parramatta Mosque.

More than a day after the 16-year-old was arrested, multiple students and parents dropping their children off said they had not been told.  

"We haven't heard anything about it," a student in year 11 said.

The 16-year-old, who is in year 10, has been released from police custody. No charges have been laid. 

The release of the year 10 student comes after another Arthur Phillip student was charged with assaulting and intimidating police, resisting arrest and using a carriage service to menace.

The charge came after the 17-year-old had posted on Facebook that he would like to see Merrylands police station "burn in hell" after Jabar was killed in a shoot-out with police following the killing of Mr Cheng.

According to students, Arthur Phillip principal Lynne Goodwin told the assembly that morning that she "did not know any more than they did", and that school counsellors were available for anyone traumatised by the events.  

The lack of information comes as parents consider withdrawing their children from the area. 

"It's not safe for our kids," kindergarten parent Deephi Devineni said. 

On Wednesday, NSW Premier Mike Baird said more has to be done to prevent young students from being recruited to extremist groups. 

"There is no doubt we have to do more [about radicalisation in schools]," he said

But, so far, the Department of Education has not released any details on how a de-radicalisation program might be instituted.

"Over the past year, the NSW government has been engaging stakeholders on a plan to tackle this issue within the wider community, including school communities," a spokeswoman for NSW Education Minister Adrian Piccoli said.

"This plan will be a whole-of-government approach and will be announced in due course."

A leading psychologist has urged the government not to delay funding a multi-systemic approach across schools and the wider community.

Professor Paul Rhodes from the University of Sydney said that simply reacting by sending in school counsellors after a critical incident such as this was not good enough.

"Sending in the counsellors after the fact is completely inadequate," he said.

"Counselling is probably the last thing you want. You want someone to be dealing with trauma from a position of strength through counselling much later on.

"In order to be pro-active, not reactive, we need to fund a multi-systemic approach, through the police, the family, the school, the mosque and much wider community based initiatives."

The Department of Education would not comment on whether it was concerned about any radical elements within Arthur Phillip High School. 

NOTE: An earlier version of this story was changed for legal reasons.