Police were looking for two more people believed to have been trapped in the Paarl printing factory on Friday, SABC reported on Saturday.

According to police spokesman, Louise du Plessis, the forensic unit as well as the dog unit were searching the wreckage for the two people.

"So far seven people have been killed, 12 injured and of those 12, two were seriously injured. We are hoping that we might find two more people today," she said.

The fire was the second this year at a plant owned by Naspers subsidiary Paarl Media.

In February a blaze destroyed a R200-million magazine printing press at Paarl Gravure in Cape Town's Montague Gardens, with no casualties.

Friday's fire broke out at Paarl Print, in the Boland town's industrial area, shortly before 8.00am.

The building housed offices, printing equipment, a bindery and a storage area, and the workers who died were trapped inside. Fire-fighters from the adjacent Cape Winelands municipality had also been called in to help.

It is still unknown how the fire started.