At least 20 people have died in the polar vortex that has hit the United States this week, the Associated Press reported Tuesday. Most of the deaths were in Texas, where an unprecedented cold spell knocked out power for millions throughout the state; three fatalities occurred as a result of a tornado in North Carolina, according to the AP. At least seven of the deaths are suspected to be from gas or carbon monoxide poisoning as people struggle to keep warm in cars parked in enclosed spaces. A family of four reportedly died in a Houston house fire trying to keep themselves warm. Texas is unique as the only state with its own power grid, largely eliding federal regulation, according to the Texas Tribune.