A 72-year-old retired soldier blew himself up in a park in the Japanese city of Utsunomiya, killing himself and injuring three other people in an apparent suicide.
A media report on Sunday in Utsunomiya said that a second explosion, separate from the blast that killed the former Self Defence Force member, caused a fire in a nearby parking lot.
It said the man’s home 8 km (5 miles) from the park burnt to the ground.
Images made available by the media showed two burnt out cars, one of which belonged to the dead man, about 200 metres (650 feet) from the park and a charred broken bench at the edge of the park, where a folk art festival was underway.
The police in the city said they had discovered a suicide note written by the man and were investigating the three incidents, but did not give further details.
Experts report noted that suicide rates have declined in Japan in recent years, but remain among the highest in the world, with around 30,000 people a year taking their own lives.
They identified financial stress of surviving on small pensions as the reason for pushing some retired people to end their lives.
They recalled that in 2015, a 71-year-old man set himself on fire on a bullet train in an incident that also claimed the life of a 52 year-old woman travelling in the same carriage.