Pupil from same school as killer charged

A student from the same high school as the teenager who gunned down a NSW police employee in Parramatta has been charged over social media posts and threatening police.

It's alleged the 17-year-old posted online his hopes that "them lil piggies get shot", and that "merryland (sic) police station is next hope they all burn in hell".

The Arthur Phillip High School student will face six charges when he fronts a children's court on November 9.

The teenager was first questioned about the posts on Tuesday morning.

"During the interaction, police allege the teenager threatened and intimidated police," police said in a statement.

He was then arrested and taken to Parramatta police station, where he was questioned for most of the day.

After being charged he was seen leaving with three officers in an unmarked car, wearing a baseball cap with his head ducked down, a witness told AAP.

Conditional bail has been granted to the boy and investigations are continuing.

The charges come four days after Farhad Khalil Mohammad Jabar gunned down 58-year-old NSW police accountant Curtis Cheng.

Students returned to Arthur Phillip High School for the start of the new term on Tuesday, commencing with a sombre assembly that addressed Friday's shooting.

Some pupils expressed disbelief while others said they were now "frightened" and "shaken".