AUSTIN, Texas (AP) — A frigid blast of winter weather across the U.S. has left more than 2 million people in Texas without power. Temperatures dropped into the single digits as far south as San Antonio and snow shut down air travel and grocery stores. The worsening conditions also halted the delivery of new COVID-19 vaccine shipments in Texas. The storm was part of a massive system that brought snow, sleet and freezing rain to the southern Plains and was spreading across the Ohio Valley and to the Northeast. The Southwest Power Pool, a group of utilities across 14 states, called for rolling outages because the supply of reserve energy had been exhausted.