Another elderly patient in Gifu Prefecture has died at a hospital where air conditioning units had broken down amid a heat wave that has gripped the country, police said Wednesday, bring the death toll there to five.

The fifth fatality was an 84-year-old male patient who passed away Tuesday evening at Y&M Fujikake Daiichi Hospital in the city of Gifu. The hospital had denied that the air conditioning failure was the cause of the four earlier deaths, saying that fans were put into use after the air conditioning units malfunctioned.

The police received a report on Monday evening that four people had died at the hospital possibly due to heatstroke after the air conditioners broke down. They have launched an investigation into the deaths on suspicion of professional negligence.