At least four people have been killed and several more are missing as heavy rain triggered landslides in the western Japanese city of Hiroshima, rescuers said Wednesday, while local media reported the death toll has reached seven.

"We haven't assessed the full extent yet but four people have been confirmed dead," said a spokesman for Hiroshima's fire department, which operates the city's emergency services.

Rescuers said the victims of the disaster which struck overnight included a two-year-old child and a 77-year-old woman.

Another emergency services spokesman said several more people were missing although the exact number was not yet confirmed.

There are "several spots where people are supposed to be buried alive, and we still don't know how many people are missing", he told AFP.

Public broadcaster NHK and private broadcaster Nippon TV said at least seven people had died.

NHK said 13 people were also missing, while Nippon TV said at least 23 were unaccounted for, citing police and rescue officials.

Television footage showed houses destroyed by landslides that tore down the mountains situated behind them, with torrents of muddy water running through the wrecked buildings.