A faulty cable triggered a major power outage in Barcelona Monday, snarling traffic, hobbling public transportation and knocking out electricity to homes and businesses in much of Spain's second largest city.

City officials said the blackout began around 11 a.m. (0900 GMT) and affected traffic lights in much of the city center as well as several lines of the subway system. Police officers manned major intersections to keep traffic flowing.

The blackout continued more than four hours later, although Red Electrica, the company that manages Spain's power grid, said more than half the power supply had been restored.

Spanish Industry Minister Joan Clos ruled out sabotage, blaming the blackout on a substation cable that fell, causing a chain-reaction failure in as many as six other substations.

Around 300,000 customers spread throughout most of Barcelona lost power, and 130,000 of them remained without electricity mid-afternoon, the minister told a news conference.

At least one major Barcelona hospital, Hospital Clinic i Provincial, was relying on generator power, said spokesman Marc de Semir. It is being used to light operating theaters, while regular hospital rooms and administrative offices were either without power or using dimmed lights to go easy on the generators, he said.