Four people were injured after a man set fire to a city hall in central Japan, police said, with local media reporting he had been arrested.

At around 3:00 pm, a man with what appeared to be a knife in his hand set fire to the city hall in Takahama, Aichi prefecture, a police spokesman told AFP.

"Around four people -- men and women -- were injured," he said, without giving further details.

The four were sent to hospital, one of them badly injured, public broadcaster NHK reported, citing local fire department officials.

The man spread what appeared to be oil on the ground floor of the city hall and set it alight, NHK said. The fire was extinguished about 20 minutes later, it said.

Arson attacks are not rare in Japan with more than 2,000 cases, or six percent of the total number of fires, reported in 2022, according to the fire and disaster management agency.

In one of the worst incidents, in 2019, a man started a fire that killed 36 people at an animation studio.