Thousands in Puerto Rico were left in the dark on Thursday following a fire at an electrical substation. This happened shortly after the power company Luma Energy reported a cyberattack that was not immediately linked to the blaze.

“There was a fire in a transformer at the Monacillo substation” in San Juan, Luma Energy said, two hours after it said it was the target of a DDoS, or denial of service, attack with two million visits per second.

Luma Energy is a new utility on the Caribbean island, starting operations on June 1 to improve Puerto Rico’s electricity transmission system.

“The fire caused significant blackouts across the island,” the company said on Facebook.

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.”

Luma Energy had said earlier on Thursday that the DDoS attack was preventing customers from accessing their accounts.

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, said on Twitter that the blackout was affecting 500,000 people and 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 was created to serve Puerto Rico — a US territory — and is jointly owned by North American parent companies ATCO and Quanta.