TOKYO, Japan (CNN) -- Police found three men dead in a car parked outside a spa Monday morning -- the latest in a string of suicides involving detergent, officials said.

According to local media reports, more than 60 people have committed suicide across Japan in the last month by mixing detergent and other chemicals, and inhaling the hydrogen sulfide gas that results.

A passerby discovered the bodies of the three men in Tamioka, north of Tokyo, police said.

In western Japan, police found a 21-year-old man with a plastic bag over his head Monday. A police officer in Suma, where the body was found, said authorities found detergent containers by the foot of the man. They suspect the man may have inhaled the toxic gas after mixing them in the bag.

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Earlier this month, police in Japan had asked Internet service providers to take down the recipe for the detergent mix. Even before the spate of recent suicides, Japan had one of the highest rates of suicide in the world.

In early May, police evacuated about 350 people from their homes on the island of Hokkaido after a neighbor mixed detergent and chemicals to kill himself.

The two most recent cases did not require the evacuation of the neighborhoods where they occurred. In some cases, officials had to order residents to leave because the resulting gas from the detergent mix can sicken people.

CNN's Yoko Wakatsuki contributed to this report

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