How we got here

The frigid air mass that settled over Texas froze wind turbines and caused natural gas producers to dial back production to protect personnel and equipment.

As part of its statewide response, the Texas Railroad Commission, which regulates oil and natural gas in the state, issued an emergency order on Friday evening to manage shortages of natural gas, requiring gas to first be delivered to residences, hospitals, schools, churches and other locations that meet human needs, then to power plants and then to industrial users.

Electricity generators in the state rely heavily on gas and wind power, and the cutbacks forced the Electric Reliability Council of Texas, or ERCOT, to declare a statewide power generation shortfall emergency. It asked electricity delivery companies to reduce load through controlled outages.

The problem was exacerbated by downed power lines caused by icing that could keep some customers in the cold and dark for an extended time.