The blast at the Stockline Plastics factory destroyed the building and injured 37 people â€” at least 16 seriously.
It's estimated about 100 people were working in the factory at the time of the blast. Workers caught in the explosion described being â€œblinded by smoke and dustâ€ and survivors described how they crawled out from the debris.
Rescuers had been using sniffer dogs, heat and ultrasound detectors to check for any victims who might have been trapped in the rubble.
The cause of the blast is unknown, although police have ruled out terrorism. There was no fire, and atmospheric tests indicated there was no airborne chemical release.
The United Kingdom's Health and Safety Executive (HSE) has a team on site assisting the emergency services and says it will be possible to begin the investigation when the site has been made safe.
The companies in charge of the factory, ICL Plastics Ltd. and Stockline Plastics Ltd., issued a statement expressing their condolences to the families of those who died in the explosion. The companies said they were working closely with the HSE to establish the cause of the explosion.