One man has been killed and three other people injured when two explosions rocked a park in Utsunomiya, a city in Japans Tochigi prefecture.

Cars in the parking area were seen burning as police and emergency personnel arrived at the scene.

There was a festival underway in the park when the explosions occurred.

The first blast took place about 11.30am local time and within a minute there was another explosion.

A badly disfigured body was discovered at the parking space.

Japans state broadcaster NHK quoted an eyewitness who said he heard a loud sound and saw three people lying on the ground. He added that he could smell gunpowder at the blast site.

The cause of the explosions is not known.

A suspected suicide note has reportedly been found at the blast location inside a vehicle, which belonged to a 72-year-old former officer in Japans Self-Defense Forces – the countrys combined military services.

Photos showing charred vehicles from the explosions have been posted on social media.

Utsunomiya is located north of Japans capital Tokyo.