Thousands of people were left in the dark following the incidents, although it was unclear if they were linked.
A fire at an electrical substation left hundreds of thousands of Puerto Ricans in the dark on Thursday, shortly after the power company reported a cyberattack that it did not immediately link to the blaze.
Luma Energy confirmed the fire at a facility in the capital, San Juan, two hours after saying it had been targeted by a distributed denial of service (DDoS) attack that stopped customers from accessing their accounts.
“The fire caused significant blackouts across the island,” the company said on Facebook.
Luma Energy is a new utility on the Caribbean island, starting operations on June 1 to improve the electricity transmission system in the United States territory.
Company chief executive Wayne Stensby said around 700,000 customers were in the dark, local daily El Nuevo Dia reported. He added that it would take all night to restore service.
Photos and videos posted on social media showed large flames and black smoke over the substation.
“All the resources of the PR government are available to handle the emergency caused by the fire at the Monacillos substation,” Governor Pedro Pierluisi tweeted. “Firefighters have already arrived on the scene.”
Pierluisi said in a later statement that state and federal law authorities were “investigating the substation explosion”.
He added that whoever was “responsible for it will be held accountable to the people of Puerto Rico”.
Officials did not say whether they were investigating a link between the fire and the cyberattack.
Jenniffer Gonzalez, who represents Puerto Rico in the US Congress, pledged an investigation.
“The fire in Monacillos, the blackout for more than half a million residents, sectors without light for a week do not seem to me to be isolated events,” she said, referring to recent episodes in Puerto Rico.
“I have alerted federal law enforcement agencies to investigate each event. They hurt the people, who are the ones who suffer.”
Luma Energy is jointly owned by North American parent companies ATCO and Quanta.