A fire has broken out at a primary school in downtown Tokyo, with all 300 or so students and teachers evacuated or rescued.

The Tokyo Fire Department said the fire at the Takinogawa No 3 Elementary School broke out near a music room on the top floor of the four-storey building late on Friday morning.

Firefighters rescued one teacher and several schoolchildren with non-life-threatening injuries, the department said.

Television footage showed black smoke billowing out of windows on the fourth floor, as firefighters combated the blaze.

Dozens of fire engines were deployed.

All others inside the building when the fire broke out had evacuated to a nearby park on their own and no one was left behind, officials said.

The cause of the fire is still under investigation.