JACKSON, Miss. — Subfreezing temperatures and widespread power outages left more people in the U.S. South stranded without basic supplies and heating as authorities worked to restore electricity and clear roads, officials said Wednesday.

In Mississippi, state officials dispatched 135 snowplows and National Guard troops equipped with wreckers to sections of Interstates 55 and 22 that were gridlocked by vehicles abandoned in ice. Tens of thousands of homes and businesses remained without power as cold daytime temperatures fell below freezing overnight in parts of the region unaccustomed to weather of that severity.

A driver described how long she sat immobilized in her car. Samantha Lewis, 78, said she feared there was no way out. “There was nowhere to go, nothing to do, no one to save us,” Lewis said.

Mississippi officials said the storm was the state’s worst winter storm in more than 30 years, and the broader emergency extended into neighboring states. Roughly 332,000 homes and businesses remained without power Wednesday, the vast majority in Tennessee and Mississippi, and at least 70 people across the United States have died in states affected by the dangerous cold.

In Hardin County, Tennessee, emergency management director LaRae Sliger said many people remained trapped in homes without electricity because roads were impassable due to ice and fallen trees. Sliger said residents who prepared to manage a couple of days without power could not go much longer without help, citing shortages of heating fuel and food. “They’re cold, they don’t have power, they don’t have heat, they’re out of propane, they’re out of wood, they’re out of kerosene for their kerosene heaters. They have no food, they have no additional fuel for their alternative heating sources, so they’re needing out,” she said.

In northeast Mississippi, Alcorn County emergency managers were receiving “calls of desperation,” said Evan Gibens, the emergency agency’s director. Gibens said dispatchers who have been sleeping at work since Friday had fielded more than 2,000 calls, and he said 200 people were staying at a local arena being used as a warming shelter. “We are doing everything we possibly can,” Gibens said.

In Nashville, Tennessee, downed trees and snapped power lines blocked access to some areas, and more than 100,000 outages remained, said Brent Baker, a Nashville Electric Service vice president. Baker said utility workers will need at least the weekend, if not longer, to finish restoring power.

Forecasters said the subfreezing weather would persist in the eastern United States into February, with another surge of arctic air arriving this weekend. The National Weather Service said the chances of additional, significant snowfall are low in places like Nashville, but temperatures over the weekend were expected to reach dangerously low single digits with wind chills below zero.

The road crisis in Mississippi began Tuesday as drivers used single lanes the state had tried to keep open for emergency vehicles. David Kenney, a spokesperson for the Mississippi Department of Transportation, said cars and semitrucks trying to navigate the frozen highways began getting stuck, and the blocked highways made it harder for authorities to distribute emergency supplies. Scott Simmons, a spokesperson for the Mississippi Emergency Management Agency, said its drivers were finding alternate routes to avoid backups, and the Mississippi Department of Public Safety said no injuries were reported.

Samantha Lewis and a friend, Catherine Muldoon, said they got stuck on I-22 at about noon Tuesday while traveling from Florida to Oklahoma. Muldoon said they turned on the car for 15 minutes to warm up and then shut it off for 45 minutes to conserve fuel. She said they followed a pickup truck on an ice-covered, traffic-free lane at about 3:30 a.m. Wednesday and reached a gas station. “It was extremely frightening,” Muldoon said. “If we didn’t have the blankets and clothing that we had, it would have been dire straits.”

The Mississippi Department of Public Safety said all passenger vehicles were cleared from the frozen highways by 3 a.m. Wednesday, though long lines of commercial trucks remained awaiting removal hours later. In the small community of Red Banks, authorities asked people with all-terrain vehicles to bring water, food, blankets or gas to stranded motorists, said Lacey Clancy. “The highway kind of looks like a parking lot,” Clancy said. “A lot of people have run out of gas, abandoned their vehicles.”

Angie Gresham, who lives in nearby Holly Springs, said hundreds of stranded vehicles were lining I-22 and city streets. She said stranded truck drivers were searching for stores and restaurants that had power, and she said many were focused on getting through the cold. “They’re just trying to survive.”