Guanica, Puerto Rico (CNN) Power is expected to be slowly restored to all homes in Puerto Rico over the coming days in the aftermath of a 6.4 magnitude earthquake that left many residents sleeping outside their homes and more than 2,000 others in shelters.

The strongest and likely most damaging of hundreds of temblors that have struck the island since December 28 hit before dawn Tuesday. It left one man dead and caused dozens of homes and other structures to crumble.

With three major power plants expected to return to service between Thursday and Saturday, Puerto Rico Electric Energy Authority CEO Jose Ortiz said the entire US territory -- with about 3 million residents -- could have power by the weekend. A fourth plant could begin operating by Sunday, he said.

A family takes refuge in Guanica.

"The target is for Saturday to have everybody with power," Ortiz told CNN Thursday.

Power has now been restored to about 700,000 of Puerto Rico's 1.4 million utility customers across the island, according to Ortiz.

Read More