One crewmember went inside the ballast tank without having previously made a gas check. On entering he lost consciousness and fell down and another crewman attempted to resce him, also losing consciousness.
Eventually a third crewmember went inside wearing a SCBA set and managed to take his two crewmates out. Rescucitation treatment was immediately commenced by the crew and as soon as emergency services showed up they immediately evacuated one of the casualties to hospital suffering from cardiopulmonary arrest.
The report states that at the time of sending it to press for publishing the evacuated casualty remained at the hospital’s ICU but a post from a reader states that he later passed away.
Staff from the Fire Brigade mobilised with medical emergency services made a check of the space’s atmosphere and reportedly found as low as 10% O2 content.