Parents across several Adelaide schools have been left anxious after the arrest of a primary school staff member now facing a historical child sex charge.

7NEWS understands the person has worked at least four separate schools and is currently employed at Brighton Primary School.

WATCH ABOVE: Parents worried about staffer charged with a historical child sex offence

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They were arrested two weeks ago.

Brighton Primary issued a letter to families on Wednesday night confirming “a staff member at our school has been arrested by police and charged with a historical child sexual offence.”

Parents arriving at the school on Thursday said they were desperate for more information.

“It was quite a shock, but yeah we had no idea and it was just a shock to everyone,” a parent said.

“How are they, these people, slipping through and getting these positions around children,” another said.

“There needs to be a better control over who is out there with our children,” another parent added.

A letter has been handed out to parents at various western Adelaide schools Credit: 7NEWS

Similar letters have been sent to families at Warradale Primary School, Paringa Park Primary School and Springbank Secondary College, advising that a former staff member connected to those sites has also been charged.

The exact circumstances surrounding the alleged offence are expected to become clearer when the school employee faces court next month.