Cuba's efforts to restore power to the island were derailed for a third time late on Saturday, Cuban authorities said shortly before midnight, leaving millions in the dark and raising fresh questions over the viability of the government's bid to reestablish electrical service.

The Cuban government has announced emergency measures to slash electricity demand, including suspending school and university classes, shutting down some state-owned workplaces and canceling nonessential services. Officials said that 1.64 gigawatts went offline during peak hours, about half the total demand at the time.