Knox CFA deputy group officer Peter Shaw said crews were alerted to the fire at 6.45 and, due to thick smoke, it took nearly 90 minutes to control it.

He said the fire started in an art supplies factory. There was no one at the site when the fire began.

The fire spread to factories on either side before it could be contained.

One firefighter suffered a minor injury when a piece of debris flew into his eye.

The contents of the art supplies factory were completely burnt and there was significant heat and fire damage to the roof.

Fire investigators continued to look into the cause of the fire today.