Tens of millions of people on Indonesia's heavily populated Java island were affected by a widespread electricity outage Sunday after the state utility PLN reported disruptions at several power plants. The shutdown plunged buildings in the sprawling capital Jakarta -- home to some 30 million people -- into darkness and forced the temporary closure of its new mass rapid transit system. Passengers were safely evacuated from several MRT carriages when the power went out, according to the system's operator, while commuter trains were also affected. Jakarta's hospitals and Soekarno-Hatta International Airport were not affected because they have backup power generators, officials said. "For people with sick relatives, all hospitals in Jakarta have power generators and are operating normally," the city's governor Anies Baswedan said on social media. Jakarta's top politician called for residents to reduce travel and conserve water until power is restored. The blackout -- which began around noon local time (0500 GMT) and was expected to last until later Sunday -- caused sporadic disruptions in mobile phone services and cash machines, while some apartment buildings were left in the dark. "The blackout has been going on for hours and it's extremely hot in my apartment because the air conditioner is off," said 30-year-old Jakarta resident Maya Larasati. Outages also turned off some traffic lights, aggravating the capital's notorious congestion. PLN said the blackout was caused when a gas turbine at a major power plant went down and by disruption at another facility. Both are on the western end of Java. "We're doing our best to fix the system so the power comes back to normal," it added.