An Adelaide man has been charged with "horrific" sex crimes against at least seven preschool children under his watch at a government-run residential care facility.

The 32-year-old man, who was employed by Families SA, has been charged with seven counts of unlawful sexual intercourse with young children.

The man, whose name has been suppressed, was also charged with the production, possession and dissemination of child exploitation material.

Police have warned that there could be more than seven victims.

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It is alleged that all seven victims were in the man's care at the residential facility but the man also cared for children outside school hours.

Assistant Crime Commissioner Paul Dickson said it was not yet clear if the alleged offender was acting alone or with others.

"As a police officer and as a father I am abhorred by these crimes," he said.

"This investigation will remain a priority for police. Due to the complexity and enormity of the data yet to be analysed, (it) may take many months to complete."

The offences identified so far occurred over 18 months between mid-2011 and the end of 2012, and police have confirmed some were committed at the care facility.

Police searched the man's house in June after receiving information that he was distributing child exploitation material.

The search revealed evidence of contact offending, they said, and led to his charges.

Detectives have analysed more than 100,000 still images and 600 video files during the investigation.

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Families SA deputy chief executive David Waterford said the accused man had undergone rigorous working with children assessment before being employed and had background checks every three years.

He described the alleged crimes as "disturbing and horrifying" and said the department would ensure all families were notified.

The accused is due to appear before the Adelaide Magistrates Court on August 19.

Concerned parents and carers should call a government hotline on 1800 659 572.

- AAP