Three women died and around 10 students were taken to hospitals Monday due to heatstroke symptoms as unseasonably hot weather continued in Japan, authorities have said.

The mercury topped 30 degrees for a fourth straight day in central Tokyo, setting a new record for May, the Meteorological Agency said.

A 42-year-old woman found unconscious behind the wheel of a car parked at a supermarket in Mito, Ibaraki Prefecture, was later pronounced dead, while an 88-year-old woman died in Hanyu, Saitama Prefecture, after being found in her field, according to local government representatives.

A woman in her 90s was also found dead in a field in Oshu, Iwate Prefecture, with local authorities suspecting heatstroke.

In Machida, western Tokyo, 24 junior high school students complained of feeling ill while practicing for sports day. Around 10 of them were taken to hospital but none were in a serious condition, police and other sources said.

Among 926 monitoring posts across the country, about 400 registered temperatures above 30 C, the agency said. Kumagaya in Saitama marked 36.2 C, while Isesaki in Gunma Prefecture logged 36.0 C, the agency said.

The heat is expected to gradually ease in the west of the country on Tuesday with the arrival of a moist air mass, it added.

The mercury also rose on the island of Hokkaido, with Obihiro marking 35.8 C. Saroma logged 32.6 C, after registering 39.5 C on Sunday — a record-high May temperature for the country.

Hokkaido Railway Co. canceled more than 100 train services Monday due to the risk of track distortion caused by the heat.