A blackout Monday in parts of Tokyo and surrounding areas left hundreds of thousands of homes without electricity and some people stuck in elevators, officials said.

At least two elevators stopped in central Tokyo with an unspecified number of people trapped in side, Tokyo fire official Keisuke Hayashi said. Kyodo News agency reported that at least people were stuck in at least 24 elevators in Tokyo.

Tokyo Power Electric Co. was investigating the cause of the blackout, which occurred at 7:38 a.m. Monday, company official Kiyohito Yokoi said.

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At least 800,000 households were affected in the blackout in Tokyo and Chiba prefecture (state), just east of Tokyo, Yokoi said.

TV Asahi said that power has been restored in most of Tokyo and Chiba.

Kyodo News agency said about 220,000 households in Kanagawa had been affected by the blackout, but that power had been restored there.

Police in Chiba were investigating an accident in which a crane truck damaged high-voltage electrical power lines as a possible cause of the blackout, Kyodo reported.

More than 260 traffic lights in Tokyo were out, Kyodo said.

Media reports said that several trains services were halted. Japan was in the middle of "bon" holiday and the number of passengers during the morning rush hour was fewer than usual.

The government set up a task force to collect information on the damage.

The Tokyo Stock Exchange began trading as usual despite the blackout. TSE spokeswoman Mariko Saito said that the bourse, located in central Tokyo, had switched to emergency power sources when the blackout occurred.