'Unprecedented' heavy rain in Japan kills at least four

At least four people died in eastern Japan after "unprecedented" heavy rain that left thousands stranded at Narita airport overnight and snarled up roads and rail services, authorities said on Friday.

The torrential downpours late on Thursday triggered landslide warnings and power outages, with forecasters issuing the highest-level heavy rain warning for the Chiba region for the first time.

As of Friday morning, close to 26,000 households across Chiba prefecture were without power, the disaster management office said.

A total of 45 houses flooded in cities like Ichikawa, Kashiwa and Sakura.

Another 39 homes saw water seeping in below the floorboards.

A Japan Meteorological Agency (JMA) official had told a news conference on Thursday that this was "shaping up to be an unprecedented level of heavy rain." Around 6,000 people were stranded overnight at Narita, one of two main airports serving Tokyo, with many trains to and from there cancelled until Friday afternoon, the Chiba disaster office said.