A fire broke out in a bar in downtown Tokyo on Sunday, killing four people and injuring 16 others, both customers and staff, a fire department official said.

"Firefighters rescued four men and brought them to a hospital but they were confirmed as dead," an official at the Tokyo Fire Department told AFP, adding that three 13 men and three women were also injured.

The blaze occurred in the bar on the second floor of a five-storey building in a narrow street of Tokyo and television footage showed black smoke pouring out of the windows.

Police and the fire department are investigating the cause of the fire. Witnesses told officials it appeared to have started in the kitchen.