SAN JUAN, Puerto Rico (AP) — Power was restored to 98.8% of customers early Friday after an island-wide blackout hit Puerto earlier this week, authorities said.

More than 1.45 million customers had electricity less than 48 hours after the outage hit, according to Luma Energy, which oversees the transmission and distribution of power on the island.

“Although restoration is nearing completion, some customers may continue to experience temporary outages due to limited generation,” Luma said.

The blackout that hit Wednesday afternoon occurred after a transmission line failed and then caused generators across the island to protectively shut down, officials have said. It also left more than 400,000 customers without water at the time.

It wasn’t immediately clear what caused the failure, although authorities are investigating whether a series of breakers failed or if overgrown vegetation is to blame.

Gov. Jenniffer González said she expected to receive a preliminary report in upcoming days.

It’s the second massive blackout to hit Puerto Rico in less than four months. The previous one happened on New Year’s Eve.