Police have charged three men over a major fire at Parramatta Public School, but they’re still searching for a fourth suspect.

The blaze resulted in more than $10 million in damages to the heritage building in May.

A thorough police strike force investigation has followed, including the release of security footage to help police find those involved.

They have now laid charges against three men, aged 19 to 20.

They’re accused of deliberately starting the fire and trespassing.

Each man has been granted bail to face court at a later date.

Detectives are still searching for a fourth suspect who’s being warned to come forward now before officers come knocking at their door.

If you have any information, you can report it anonymously to Crime Stoppers on  1800 333 000.