A power cut suspended multiple train services in Tokyo on Tuesday morning, with nine passengers taken to hospital after becoming unwell as the air-conditioning system on their train failed, a railway operator and rescuers said.

The 8:30 a.m. power outage left eight trains stranded between stations on the line run by Keisei Electric Railway Co., as well as the Toei Asakusa Line and the Hokuso Line.

In total, 15 people in their 20s to 60s complained of symptoms such as numbness in the hands and feet and dizziness, the Tokyo Fire Department said. Temperatures had already soared to 32.5 C in central Tokyo at 9 a.m.

Nine people on an eight-car train which had stopped between Yotsugi Station and Yahiro Station on the Keisei Oshiage Line were taken to hospital after claiming they felt unwell. All remained conscious.

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"After the air-conditioning system stopped, it became so stuffy," said a 34-year-old woman who was stranded on the train.

According to Keikyu Corp., which owns the train, the backup power source was only enough to power radio equipment and fans, and could not run the air-conditioning system. Passengers could only open the windows.

Around 900 passengers exited the train from the first carriage onto the tracks, and were guided to Yahiro Station, located around 50 meters away, on foot.

Some trains on the Keisei Main Line, Oshiage Line and Kanamachi Line were also temporarily suspended and all passengers alighted from the stranded trains in around two hours, the operator said. The Asakusa Line and Keikyu trains also experienced suspensions and delays.

"An announcement told us to open the windows, and passengers worked together to do so. After we exited onto the tracks, I felt scared when I saw people being taken away on stretchers," said a 54-year-old woman who had been on a suspended train.

At Keisei's Narita Airport Terminal 1 Station, staff advised people heading to Tokyo to use JR lines or buses instead.