Harlingen, Texas (Nexstar) – At least two million people lost power during the severe weather that brought winter storm warnings to each of Texas’ 254 counties, according to the manager of the state’s power grid.

Though enough power was built back up to restore service to 500,000 Texas households, leaders with the Electric Reliability Council of Texas (ERCOT) said controlled outages “will likely last throughout the evening and into tomorrow as ERCOT works to restore the electric system to normal operations.”

“If we don’t have more supply, the only thing we can do is start to reduce demand on the system,” Dan Woodfin, ERCOT’s senior director of systems operations said.

Reports of power outages in the Rio Grande Valley started at 9:30 p.m. Sunday night, and have continued through Monday.

This historic storm has drawn comparisons to other historic weather events.

“It’s the electricity and storm equivalent of the 100 year flood people talk about” said Andrew Barlow, Public Utility Commission spokesperson.

Barlow explained that the mass power outages were caused by generation companies going offline due to the cold, ice causing power lines to fail and the high demand from customers to keep their houses warm.

In order to save energy, generation companies began rolling outages, but Barlow said these are different from what people are used to.

“Rolling outages may only take 30 to 40, or 60 minutes per household,” he said. “In this case, the outages and the loss of that electricity was so severe that some of these outages have had to go longer than desired.”

“Unfortunately, because the excessive demand and the loss of those generation assets due to various causes, we’re just in a tough spot right now,” Barlow said.

The Electric Reliability Council of Texas (ERCOT) has ordered blackouts across the state to preserve power. The generators are facing a shortage of natural gas, wind, and solar to maintain the power grid.

“The operational facilities froze up,” Gov. Greg Abbott said on Monday. “And this includes our providers ranging from natural gas to coal to all different forms of energy.’

Abbott announced the deployment of resources Saturday to respond to the winter weather. He also requested a federal emergency declaration, which the White House approved.

Barlow asks those that still have power to conserve it by keep the thermostat under 68 degrees, unplugging unused devices, avoid using appliances which draw large amounts of electricity like dishwashers, washing machines and driers, and close the blinds to keep the heat in your home.

“If your electricity is off, just know that people are working very hard to get your power back home,” he said. He encouraged families that don’t have the power to look into shelters that have power generators and can keep them safe.