A fire in the Haifa subway, the Carmelit, may have been caused by routine maintenance, according to the team investigating the blaze, which began in the Paris Square station.
Thirteen firefighter teams fought the flames before the fire was brought under control.
The 6-station system, which made its debut in 1959, was renovated in 1992 and climbs 1.8 kilometers up the tiers of Mount Carmel.
A 70-year-old woman in one of the neighborhoods served by the underground railway was treated for smoke inhalation.
Two cars caught on fire, and heavy smoke spread through the system to other underground stations.
Although the system does not operate on Saturdays, rescue workers checked the entire system anyway and told the Israel Electric Company to shut down power in surrounding neighborhoods to be on the safe side.
Haifa Mayor Yona Yahav has appointed the city’s municipal director-general to lead the process of getting the subway back in action.