TOKYO —  A heat wave sent temperatures soaring to 95 degrees in much of Japan on Friday, killing three people and forcing hundreds to seek treatment at hospitals, officials and news reports said.

About 400 people, including high school students attending a baseball game in Utsunomiya, were treated at hospitals for heat stroke symptoms, public broadcaster NHK reported.

In the southern port of Nagasaki, a 60-year-old woman was found dead outside her apartment, police spokesman Yasuhiro Motomura said. In Aichi, an 88-year-old man collapsed in a vegetable field and was taken to a hospital, where he was pronounced dead.

A 29-year-old construction worker collapsed in Saitama, near Tokyo, apparently after developing heat stroke, and died later at a hospital, NHK said.

Friday was the hottest day of the year in much of the country due to high pressure hovering above the Pacific Ocean south of the Japanese archipelago.