A National Crime Agency boss spoke to the Herald about the discovery of a major gun factory in a Hailsham industrial estate.
Armed police swarmed Diplocks Way on Saturday night (August 18) after loud bangs - believed to be gunshots - were heard coming from an engineering workshop.
According to the NCA, three men were arrested and two handguns seized at the scene.
The NCA's Rob Hickinbottom, head of the National Firearms Threat Centre, today (Wednesday) held a press conference at the site.
Speaking to the Herald he said, "Our officers from our armed operation unit attended the premises here behind me.
"Whilst here they heard two loud bangs which they determined to be gunshots. So they have made the decision, having heard
those sounds, to make arrests of persons when they exited the premises."
An officer was hurt in the process and a tazer was used in order to make one of the arrests, he told the Herald.
"So within the premises what we've discovered is a manufacturing of firearms," he said, "We have discovered upwards of 30 handguns and blueprints to make those weapons."
"It's rare across the country, not just in Hailsham. It's very unusual to find weapons being made from scratch. And certainly to the numbers that we've discovered here."
The area around the industrial unit was cordoned off, and NCA and Sussex Police officers began a thorough forensic search of the site.
That search has taken several days, but officers have found what they suspect to be machinery and components used in the criminal manufacture of firearms and ammunition, including a number of handguns in various stages of production, as well as what appears to be templates and metal for use in their fabrication.
Mr Hickinbottom said NCA officers have also searched other premises in connection with this investigation, but would not give any further information as to where they were.
All three men who were arrested were later charged with offences relating to the possession of firearms and have now been remanded in custody after appearing before a magistrate, said the NCA.