Most of Puerto Rico has no power following a blackout, cause unknown

Crews are continuing to work Thursday in Puerto Rico to restore power after the island was hit by a blackout that has impacted hospitals and the main international airport.

As of now, the cause of the blackout is not known.

The outage happened during the day on Wednesday and resulted in 1.4 million customers being without electricity, according to CBS News.

Hundreds of thousands of people don't have water. 

The local utility, Luma Energy reported that as of 6 a.m., about 609,000 customers now have service restored. 

"Our crews will continue working throughout the day today with the goal of restoring service to 90% of our customers within 48 hours, conditions permitting," the company said. 

Luma Energy said it was investigating the cause of the blackout. 

The blackout is the second island-wide blackout that has hit Puerto Rico in four months.