On December 17, 2021, an arsonist dispersed gasoline and set a fire in a mental health outpatient clinic in Osaka, Japan. 26 people (i.e., a psychiatrist, clinic staff, and patients with mental disorders attending the clinic’s daycare program) were killed by carbon monoxide poisoning. The arsonist, reported to be this clinic’s patient, also died in the event.

Arson cases have been known documented since ancient times. In modern Japan, arson cases have been decreasing (6615 cases in the year 2009 v. 2757 cases in the year 2019). ¹ However, mass violence using flammable liquids has become an urgent social concern in recent years. In 2019, a man stormed into the Kyoto Animation studio building in Kyoto. He used tanks of gasoline to start a fire that killed 36 people and injured 34 others. Since then, flammable liquid attacks in the public spaces became frequent. In March 2021, an arsonist in Tokushima used gasoline in his attack on a concert venue. In October 2021, a train passenger in Tokyo stabbed a stranger, strew lighter fluid, set the train on fire, and injured 17 people. Flammable liquids are publicly available, easy to use, and can instantly harm dozens of innocent people.

The tragedy in Osaka highlights lessons for mental healthcare professionals. First, the professionals need to assure the safety and security of their healthcare facilities, update their disaster preparedness plans, educate their staff, and conduct evacuation exercises. Second, mental health support for arson survivors is essential. Many survivors are expected to be resilient, but they may face more difficulties with processing their psychological trauma due to the malevolent nature of the event. ^{Reference Goldmann and Galea2} Comprehensive support to those directly affected (e.g., the bereaved, survivors, first responders, and healthcare workers) will be needed. Outreach and surveillance health systems will be useful if feasible. ^{Reference Brewin, Fuchkan and Huntley3}

Third, the target patient population will be even larger than the directly affected individuals—support for the clinic’s regular outpatients will also be crucial. Individuals with pre-existing mental disorders are already at a higher risk for post-disaster psychiatric sequelae. ^{Reference Goldmann and Galea2} While these patients may not directly witness the killing, abruptly losing their healthcare professionals will leave them no choice but to find other facilities for their future care. Additionally, emotional identification with the deceased is associated with adverse mental health consequences ^{Reference Herberman Mash, Ursano and Benevides4} and can lead to negative posttraumatic consequences (e.g., guilt, helplessness, avoidance of speaking out, lowered sense of safety). Mental support programs—with emphasis on trauma- and grief-focused interventions—will be essential. Mental healthcare workers may restore the patients’ sense of safety and help them understand that it is never too late to speak about their loss-related thoughts and emotions.

Lastly, the public should be careful not to stigmatize people who need mental health support. A few people may stereotype all psychiatric patients as “dangerous” and increase attempts to ostracize these populations. However, the arsonist for the Osaka event was an exception and not the norm for psychiatric patients. Government and community leaders should take every effort to stabilize their communities, strive for justice, and protect the vulnerable.