Eleven people died and 5,664 people were taken to hospitals in Japan due to heat-related medical issues last week when temperatures rose sharply following the end of the rainy season in most areas, the government said Tuesday.

The number of people sent to hospitals nearly tripled from 1,948 in the preceding week. Those age 65 and older accounted for 52.6 percent of the total in the week to last Sunday, according to the Fire and Disaster Management Agency.

Of the 5,664 people, 119 displayed severe symptoms that would normally require at least three weeks of treatment as an inpatient, while 1,792 suffered less serious issues, necessitating shorter stays.

The 11 deaths were reported in 11 different prefectures. Aichi Prefecture had the most people rushed to hospitals at 392, followed by Osaka Prefecture at 388 and Tokyo at 299.

In Osaka, 28-year-old Yohei Yamaguchi died on Sunday due to heatstroke after wearing a mascot costume and doing a dance lesson at Hirakata Park, an amusement park in Hirakata, the prefectural police said Monday.

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A female worker called the 119 emergency number around 8 p.m., as Yamaguchi, a part-time worker, lost consciousness. He was practicing a dance outside for about 20 minutes from 7:30 p.m. while wearing the 16-kilogram mascot costume.

Hirakata Park said it will investigate the causes and implement preventive measures, including the cancellation of all mascot costume events this summer.

Hirakata’s highest temperature on Sunday was 33.2 C, and the figure was at 28.7 C at 8 p.m., according to the Meteorological Agency.

Monday also saw more than 400 people rushed to the hospital, with Tokyo seeing the largest number at 121. Three people, ranging in age from their 60s to 80s, showed serious symptoms.

The highest temperature of 37.2 C was recorded in the town of Ibigawa, Gifu Prefecture. The temperature also hit 37 C in Kamaishi, Iwate Prefecture.

About 80 percent of the 926 monitoring posts across the nation marked 30 C or higher, the Meteorological Agency said.

The temperature between Monday 6 p.m. to Tuesday 6 a.m. in the city of Sapporo did not go below 25 C, the first time that has happened in five years.

According to the agency’s provisional assessment, the rainy season ended in the southern Tohoku region on Tuesday, five days later than in the average year. This makes northern Tohoku the only region still in the rainy season.

As temperatures are likely to remain above average in Japan in the upcoming week, the agency urged people to stay hydrated and take occasional breaks.