The death toll in Dinajpur boiler blast incident rose to four as another labourer Rustam Ali, 45, died at Rangpur Medical College Hospital (RMCH) today, police and hospital sources said.Earlier, injured labourers of Jamuna Auto Rice Mills at Sheikhhati Goplaganj under Sadar upazila in Dinajpur Ranjana Roy, 40, and Moksed Ali, 48, died on Wednesday and Ariful Islam, 30, died on Thursday died at RMCH.Head of the Department of Burn and Plastic Surgery at RMCH Dr Maruful Islam today told BSS that 15 injured labourers are undergoing treatments at the Burn and Plastic Surgery Unit in the hospital.“Conditions of 13 patients with up to 90 per cent burnt areas in their bodies are still critical --- they are facing severe breathing problems,” he said adding that conditions of the other two admitted patients were out of danger.“We have been providing the best possible treatments to all 15 patients keeping them on intensive observation round the clock,” said Director of RMCH Dr Moudud Hossain Rabu.According to police sources, some 40 labourers were injured in boiler blast at Jamuna Auto Rice Mills at Sheikhhati Goplaganj in Dinajpur at 11 am on Wednesday.Injured persons were first rushed to M Abdur Rahim Medical College Hospital in Dinajpur and later, 19 of them shifted to RMCH where four critically labourers succumbed to their injuries so far, police said.Source: BSS