The blackout was caused by a failed transmission line and possible failures in protective systems, as well as issues with vegetation management on transmission lines. Officials are investigating whether breakers failed to open or exploded, and whether overgrown vegetation affected the grid, which should not have happened.

The blackout left 1.4 million customers without electricity and more than 400,000 without water, affecting hospitals, businesses, the main international airport, and hotels on the island.

Governor Jenniffer González criticized Luma Energy, which oversees transmission and distribution, and promised to cancel contracts with energy providers like Luma Energy and Genera PR. She returned early from vacation to oversee the situation and called the blackout unacceptable.

Governor González estimated that the major outage caused an estimated $215 million to $230 million in revenue loss daily. The ongoing outages also threaten to scare away potential investors needed for economic development.

By April 17, more than half of the affected customers had power restored, with officials expecting 90% power restoration within 48 to 72 hours of the outage. Investigations are ongoing to determine the precise causes, including checking maintenance practices such as air patrols over transmission lines and protective system failures.