» Millions of Texans have their power restored as generators restart.

About 340,000 customers across the state still without electricity, down from 4 million

Rolling blackouts came to an end Thursday — at least for now — as power generation knocked out by the severe winter weather came back online and utilities quickly restored power.

Fewer than 20,000 Houston area customers were without power Thursday evening, down from a peak of about 1.4 million, according to the utility CenterPoint Energy. About 340,000 customers across Texas were without power, down from a peak of more than 4 million.

CenterPoint said it expected to restore power to nearly all its customers by the end of Thursday. Other isolated outages should be addressed by the end of Friday, the utility said.

“From the outset of the severe weather and generation shortage event, we said that we would be ready to deliver power as soon as it was available to be delivered,” said Kenny Mercado, executive vice president of electric utility at CenterPoint. “And we have done that and will continue to do so as safely as possible.”

Power was cut to millions of Texans this week as frigid temperatures knocked more than half the state’s power generation capacity. The power grid was on the edge of catastrophic failure that could have crippled the electric system for months had operators not acted quickly to cut power when power plants began failing early Monday, said Bill Magness, CEO of the Electric Reliability Council of Texas, or ERCOT, the state grid manager.

Operators had “seconds or minutes” to react to sudden loss of power supplies as frigid temperatures knocked generators offline one after the other, said Magness. Supply and demand must be balanced, or the grid could collapse.

“If operators wait, what happens that next minute might be that three big units come off and then you are sunk. We were at a level of frequency that needed to be addressed immediately and

that is what our operators did,” Magness said. “It would have been seconds and minutes (before disaster) given the amount of generation that was coming off the system at the same time as demand was still going up significantly.”

ERCOT said it was able to restore power more quickly than expected because the amount of available generation grew as temperatures lowered demand.

“We started to tell transmission owners to please restore 1,000 megawatts of load,” said ERCOT senior director of system operations Dan Woodfin. “Once they were done, and we still had enough generation, we issued an order to restore another 1,000 megawatts.

“We recognized that we had more generation coming online. We realized we could go much faster," said Woodfin.

As the outages were decreasing, the Public Utility Commission of Texas on Wednesday evening ordered that customers can't be without power more than 12 hours during rolling outages. The order applies to transmission and distribution utility entities including CenterPoint.

Some outages remain throughout the state, however, due to ice storm damage on transmission systems. Crews are working to manually reenergize the lines in areas taken out of service due to the emergency outages.

Large industrial facilities that voluntarily went offline are still without power. Some level of rotating outages may be needed over the next couple of days to keep the grid stable, particularly if some generation goes back offline, ERCOT officials said.

“We are not out of the woods yet,” said Magness. “We are still in very cold conditions. We are still seeing much higher than normal winter demand. We are keeping a close eye on it.”

ERCOT manages the flow of electric power to more than 26 million Texas customers, representing about 90 percent of the state's electric load.