Blackout hits Puerto Rico after explosion at main power substation near San Juan

SAN JUAN, Puerto Rico -- A blackout has hit northern Puerto Rico after an explosion set off a big fire at a main power substation in the U.S. territory.

Officials with the island's Electric Power Authority said late Sunday that several municipalities are without power, including parts of the capital of San Juan. It was not immediately known what caused the fire.

San Juan Mayor Carmen Cruz tweeted that no injuries have been reported yet and that firefighters are on the scene.

The blackout comes as more than 400,000 power customers remain in the dark more than five months after Hurricane Maria.

Puerto Rico's governor recently announced that he plans to privatize the state-owned power company.