A heat wave sweeping South Korea claimed two more lives, bringing the number of heat-related deaths to four in just three days, health officials said Friday.

The number of people suffering from heatstroke or other heat-related illnesses also reached 172, more than four times higher than 41 last week, according to officials from the Korea Centers for Disease Control and Prevention (CDC).

One of the latest fatalities was a 70-year-old man, who reportedly passed out on Thursday while working on his farm in Goseong, a small town located some 460 kilometers southeast of Seoul.

The exact cause of death has yet to be identified, but CDC officials said the man had likely suffered dehydration and heatstroke.

The other heat-related death involved a 79-year-old woman in Gimje, located some 260 kilometers southwest of the capital, who is also believed to have suffered heatstroke while working on her farm on Thursday.

The latest fatalities follow the death of a 34-year-old construction worker on Tuesday, marking the first heat-related death of the year, and an 87-year-old woman who died Wednesday while working on her farm in Suncheon, South Jeolla Province.

Heat wave warnings have been issued in various parts of the country with temperatures expected to reach over 36 degrees Celsius in eastern Gangwon Province and well over 33 degrees Celsius in many other parts of the country.