CARACAS (AP) ― A power outage hit nearly half of Venezuela on Tuesday, knocking out traffic lights and causing chaos in the streets of Caracas.

Deputy Energy Minister Franco Silva said failures on several transmission lines were to blame for the blackout and told state TV that nine of Venezuela’s 23 states were affected.

Venezuelans have been struggling with worsening blackouts for several years, but the capital is almost always spared.

President Nicolas Maduro said the oil industry, the lifeblood of the economy, was not affected by the outage.

The capital’s subway service was temporarily interrupted, and authorities evacuated riders from several trains.

Opposition politicians say the government hasn’t invested enough in the electrical grid and generating plants to keep up with growing demand.

Authorities say delays in several initiatives designed to boost electricity output are partly to blame. But they also have often suggested that government foes sabotaged the grid, and Maduro raised that as a possibility for Tuesday’s blackout.