A further six police officers had to be treated by medics on the day after a fatal ammonia leak at the Carlsberg factory in Northampton.
Last week tragedy struck at the Bridge Street brewery, when a gas leak claimed the life of a worker in his 40s.
Another worker, aged 51, remains in a serious condition in hospital.
Speaking to the Chronicle & Echo this week Colin Wells, the Fire Brigades Union’s serious accident investigator for Northamptonshire, said the investigation at the factory was likely to continue for some time as there are “several strands” of enquiry.
It has already been confirmed that nine firefighters also had to be rushed to hospital with breathing difficulties on the day of the incident - Wednesday, November 9.
But Mr Wells said a further six police officers has to be treated by medics the following day.
The Chronicle & Echo had made enquiries to the East Midlands Ambulance Service as to why three ambulances had arrived at the Carlsberg factory at around 1.30pm on Thursday, November 10.
The service had said the blue light response was simply part of the “ongoing incident.”
Speaking about the day of the gas leak itself, Mr Wells praised the actions of the fire fighters at the scene, who he said were: “Exposed to dangerous levels of ammonia while rendering assistance to other fire fighters using gas-tight suits.”
The crew had to make three “rescues” in what he said were “arduous” conditions on entering the factory, though sadly one rescue attempt was unsuccessful.
The post-mortem of that man, in his 40s, took place on Tuesday, though his name is yet to be released by police.
While there were also rumours that one of the fire fighter’s breathing equipment had failed during the operation, Mr Wells said that was completely untrue.
A spokeswoman for Northamptonshire Fire and Rescue, added: “We can confirm that the breathing apparatus equipment did not fail to work while crews were attending the incident and there was no interruption of air supply.
“Nine firefighters attended hospital as a precautionary measure, acting on medical advice given at the scene by a doctor. All firefighters who attended hospital were given the all clear and were sent home.
“An investigation is being carried out by Northamptonshire Fire and Rescue Service, working with the Fire Brigades Union, into these events.”