At least seven large electricity pylons collapsed onto a highway near the South African capital of Pretoria, causing a multiple-vehicle crash, city authorities and emergency services said Monday.

Two people were "moderately" injured in the car crash, treated at the scene and taken to the hospital, the private Promed paramedic service said.

The pylon collapses had caused high-voltage cables to "hang extremely low over the highway," causing vehicles to swerve to avoid them and resulting in the crash, Promed said.

The City of Tshwane, which oversees the Pretoria metropolitan area, said the pylons collapsed Sunday night.

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The reason for their collapse was unclear but Tshwane mayor Cilliers Brink said there is a "very strong possibility that this is because of criminal vandalism."

There had previously been attempts to steal sections of metal from the base of the pylons, Brink said, and the pylons had to be repaired.

Many areas in north and east Pretoria had lost their electricity supply. Repair crews were battling rainy weather and there was no estimate yet for how long those areas would be without power, the city said.

Part of the N4 highway, which is the main route into Pretoria from the east, was closed.