Record-breaking torrential rain pounded Chiba Prefecture in the Tokyo metropolitan area, leaving four people dead and one missing.

With railways and roads cut off in various places, about 7,000 people were stranded at Narita Airport and spent the night there.

Japan's NHK reported that as of this morning, the heavy rain that began the previous day in Chiba Prefecture resulted in four deaths, one missing person, and one person in a state of cardiac arrest.

Starting yesterday afternoon, torrential rain exceeding 100 mm per hour poured down on Chiba Prefecture. Chiba City recorded 348 mm of rain over a 12-hour period, the highest precipitation since weather observations began and nearly three times the average total precipitation for the entire month of August.

The Japan Meteorological Agency issued a Level 5 heavy rain special warning, the highest level of disaster alert, for parts of Chiba Prefecture.

The heavy rain also paralyzed the metropolitan transportation network, suspending operations on some lines of JR East and Keisei Electric Railway, while restricting traffic on multiple expressways.

Due to disruptions in train and bus services, it was estimated that about 7,000 travelers were stranded at Narita Airport as of 4 a.m. today.

To accommodate residents and travelers who could not return home, Chiba Prefecture opened 17 facilities, including the Chiba Prefectural Government building, as temporary shelters. About 4,000 people spent the night at these facilities, and the total number of people unable to get home across Chiba Prefecture reportedly reached 10,000.

Experts analyze that the downpour was caused by extreme atmospheric instability resulting from a low-pressure system transformed from the 15th typhoon Chanthu, combined with warm, moist air supplied by surrounding high-pressure systems meeting cold air aloft.

Strong rain clouds were found to have developed repeatedly near Chiba Prefecture.

The Japan Meteorological Agency warned that risks of landslides and lowland flooding remain in areas that received heavy rainfall, urging continued caution.

Reported by Kim Taewon | Video by Lee Da-in | Graphics by Yang Hye-min | Produced by SBS Digital News