One person has been killed, and at least three injured after multiple explosions went off in the Japanese city of Utsunomiya, some 100 kilometres north of Tokyo.

The explosions occurred around noon on Sunday in the vicinity of Utsunomiya Joshi park. One person was found dead at the scene with his body severely damaged.

A possible suicide note was found in one of the cars left burning. Local police said that car belonged to a 72-year-old man, who had previously served as an officer for Japan's Self-Defense Forces. Public broadcaster NHK said the man's house had burned down Sunday morning at around 11 a.m. and he had been uncontactable since.

Further investigation into the case is still underway.