Four people, two of them firefighters, were in a serious condition at the burns unit of St James's Hospital in Dublin following the explosion in a tyre-recycling factory in Co Louth at the weekend.
Seven people were injured when the explosion occurred inside the Crumb Rubber plant in Dromiskin around 9.30am on Saturday. The other three were treated in Our Lady of Lourdes Hospital in Drogheda and were described as being in a stable condition yesterday.
A crew from Dundalk fire station was on the premises at the time fighting a smaller machinery fire. The explosion occurred in a rubber dust silo just a few feet from them and caused serious facial burns to the firefighters and a number of staff, including one of the owners of the company.
The Health and Safety Authority is investigating the accident and a spokesman said that it would draw up a report and if appropriate the report would be forwarded to the Director of Public Prosecutions.
The explosion, which led to a second more serious fire, was inside a silo where dust made from tyre rubber had been collected.
The first fire was reported just after 8.30am and a crew from Dundalk fire station was sent to deal with it, but according to Joe Lumsden, assistant chief fire officer for Louth , when the explosion occurred they called in assistance from Drogheda, Dunleer and Dundalk.
Speaking at the scene, Mr Lumsden confirmed that the explosion had taken place beside where the first crew had been working. "We now have the fire under control and it is contained. We have a major breathing apparatus operation going on at the moment," he added.
Thick black smoke was billowing from the side of the factory and there were what seemed to be large fire or scorch marks on piping adjacent to it.
Ambulance crews from the Health Service Authority (North East) also attended. They dealt with the seven casualties and took them to Our Lady of Lourdes Hospital for treatment. Later that day, four of the injured were transferred to St James's Hospital.
Two inspectors from the HSA were on site all day Saturday. As part of their investigation they will interview those involved, including the fire crews, examine the scene forensically, take samples of evidence away for further examination and then draw up a report.
Around 35 people are employed at the plant, which had earlier this year said it would have to cut staff numbers unless it could find more tyres to recycle.
The recycling process involves reusing hi-tensile steel - which makes up one-third of a tyre - in the metal industry while the rubber is reprocessed and used on golf courses and in safety mats. Last January, company spokesman Pádraig Hand said the equestrian market was their biggest. Mr Hand is understood to be one of those injured in the blast.