San Francisco's Public Utilities Commission is investigating a power cut that may have been caused by vandalism.

The Treasure Island power cut affected the whole island early Tuesday morning. Power has since been restored.

It comes after a number of high-profile power cuts were caused by vandalism in Washington and North Carolina recently—leaving tens of thousands of homes without power—stoking fears of a new form of terrorism on American soil.

A spokesman for the SF utilities commission said: "The cause appears to be equipment failure. The cause of the equipment failure is under investigation, including whether or not the equipment failure was caused by vandalism. Crews have completed repairs and power has been restored."

This is a developing story.