The HSE, after being notified of the incident by Essex County Fire and Rescue Service, began its investigation into the fire and subsequent explosion at the site. This includes investigating factors that may have contributed to the fire and explosion, as well as other aspects relating to the site and incident response. The investigation is being carried out in close cooperation with Essex County Fire and Rescue Service, which is leading the response to the incident. A spokesperson for HSE said: "The Health and Safety Executive (HSE) was notified by Essex County Fire and Rescue Service of an incident at an industrial unit at Highlands Farm, near Rettendon in Essex. "HSE has now formally opened an investigation into the explosion."