A man triggered panic in a northern Japanese city Thursday when he killed himself by mixing detergents in his house, releasing toxic fumes that drove 350 people from their homes — the latest in a series of such suicides.

The panic in Otaru came just hours after national police urged Internet providers to crack down on Web sites that have spurred a wave of detergent-related suicides. Some 50 people have reportedly killed themselves over the past month in Japan by mixing household chemicals to produce hydrogen sulfide.

The method, the latest in a series of suicide fads in Japan in recent years, is even being used as a weapon. A farmer in another part of northern Japan was arrested Thursday for allegedly trying to kill his 82-year-old mother with the gas, police said.

The farmer in Kori, Nobuya Matsuno, was mixing toilet cleaner with mothballs in a bucket Wednesday when his father caught him and called police, a Fukushima police spokesman said, speaking on condition of anonymity in line with police policy.

In Otaru, on the northern island of Hokkaido, a 24-year-old man mixed the chemicals in his house after midnight. He died and the gas escaped his home. Neighbors were alerted by the smell, a Hokkaido police official, also on condition of anonymity.

The man's 58-year-old mother, apparently overcome by the fumes, was found unconscious nearby and was taken to a hospital, but police said she was recovering. About 350 people in the neighborhood fled to a nearby school playground where they waited for about two hours.

These cases came a week after at least 90 people were sickened by fumes in an apartment building in southwestern Japan when a teenage girl killed herself by mixing laundry detergent with cleanser in her bathroom.

On Wednesday, Japan's National Police Agency urged Internet providers to delete materials from Web sites showing readers how to mix the chemicals. Some sites reportedly provide "poison gas" warnings that viewers can print out and hang outside their doors when they kill themselves.

"Since April, the number of such Web sites has just jumped. They are rife on the Internet. Writing examples include 'you can die easily and beautifully,"' said Seiji Yoshikawa, deputy head of the Internet Hot Line, which reports suspect Internet sites to the police.

The police request was the first action taken by state authorities against detergent suicides. Japanese news media have counted more than 50 such suicides in April alone, though no official statistics have been released.

Hydrogen sulfide gas is colorless and characterized by an odor similar to that of rotten eggs. When inhaled, it can lead to suffocation or brain damage.

"What's making the problem so grave is that rescuers and neighbors could be seriously affected," the Asahi newspaper said in an editorial Thursday. "Considering the seriousness of the issue, we cannot waste any time in launching preventive measures."

With one of the highest suicide rates in the world, Japan has battled a series of suicide fads over the years. Many cases have involved victims who found each other on the Internet and committed suicide together.