Rolling power blackouts were ordered across Texas early Monday morning as a winter storm gripped the state.
The rotating outages will likely last throughout Monday morning and could continue until the state's weather emergency ends, said the Electric Reliability Council of Texas (ERCOT), a major grid operator that controls about 90% of the state's electric load.
Rotating blackouts occur when power companies cut off electricity to residential neighborhoods and small businesses, typically for 10 to 45 minutes before being rotated to another location, ERCOT said. Traffic lights and infrastructure may also lose power during these blackouts.
Rolling blackouts are sometimes used in California during heat waves, but extremely cold weather forced the action in Texas, where the winter storm has already knocked out power to more than 2.6 million customers, poweroutage.us said.
Temperatures in the high teens were predicted for Dallas on Monday, while Houston was expecting a high temperature in the mid-20s.
The City of Houston said the storm may be here several days and people may experience a rolling blackout more than once.
The city recommended people conserve energy by turning down the thermostat to 68 degrees Fahrenheit, unplugging nonessential lights and appliances, opening curtains in the day to allow sunlight and closing curtains at night to reduce heat loss.
Houston Police Department Chief Art Acevedo said the rolling blackouts caused several police facilities to operate on emergency generators.
"Please reduce the load on the electric grid by keeping use to a minimum," Acevedo tweeted Monday.
The ERCOT ordered the rolling outages around 1:30 a.m. local time (2:30 ET) Monday. ERCOT set a new winter peak demand for electricity between 6-7 p.m. Sunday, topping the old record from January 2018, ERCOT said in a tweet.
"We are experiencing record-breaking electric demand due to the extreme cold temperatures that have gripped Texas," ERCOT President and CEO Bill Magness said in a news release. "At the same time, we are dealing with higher-than-normal generation outages due to frozen wind turbines and limited natural gas supplies available to generating units."
Entergy Texas, which provides power to approximately 461,000 customers across 27 counties in the state, according to its website, said it started the rolling outages on Monday.
"We apologize for the inconvenience these outages may cause, but we have an unusual situation right now driven by extreme weather conditions. We are working to respond and restore power as soon as it is safely possible," said Stuart Barrett, vice president of customer service.
"While our crews worked to prepare for this storm, a loss of generation combined with the peak load has caused a strain on the system. As a result, we are short of the power needed to meet our customers' demands across southeast Texas."
CNN meteorologist Tyler Mauldin contributed to this story.