The emergency response in Mississippi and neighboring parts of Tennessee escalated Wednesday as subfreezing temperatures and widespread power outages left residents and motorists struggling to stay warm and supplied. Mississippi Department of Public Safety officials said Interstate 55 and Interstate 22 remained gridlocked by abandoned vehicles in the state’s northern region, prompting the state to mobilize snowplows and National Guard troops equipped with wreckers to push through the ice.

Mississippi officials reported that cold conditions continued to intensify the risk as daytime temperatures fell below freezing overnight. They said tens of thousands of homes and businesses were still without power, including in Tennessee and Mississippi, where officials warned that people stuck at home were running low on food, medicine and other essentials.

Mississippi State officials said the interstate impasse began Tuesday when drivers began using single lanes that the transportation agency had been trying to keep open for emergency vehicles. Vehicles became stuck, making it harder for authorities to distribute emergency supplies, and prompting transportation officials to describe the effort as increasingly complicated by the highway backups.

Mississippi Department of Public Safety said no injuries were reported on the frozen highways during the period of the gridlock, but it also described the dangers motorists faced. Samantha Lewis, 78, told The Associated Press that with no place to go, she feared she might freeze to death on Interstate 22 after her car sat idle for more than 14 hours, while Catherine Muldoon said the situation was “extremely frightening” and that the blankets and clothing they had helped keep things from becoming “dire straits.”

In Hardin County, Tennessee, emergency management director LaRae Sliger said many residents remained trapped in homes without electricity because roads were made impassable by ice and fallen trees. She said residents who planned for only a couple of days without power could not manage much longer, describing shortages that included propane, wood and kerosene for alternative heaters, as well as food and additional fuel for backup heat sources.

In northeast Mississippi, emergency managers in Alcorn County said they were fielding “calls of desperation” from people running out of food, water, medication and other supplies. Evan Gibens, the emergency agency’s director, said dispatchers who had been sleeping at work since Friday fielded more than 2,000 calls, and he said about 200 people were staying at a local arena being used as a warming shelter.

In Nashville, Tennessee, officials and a utility executive said outages were still leaving more than 100,000 customers without power. Brent Baker, a vice president for Nashville Electric Service, said downed trees and snapped power lines blocked access to some areas, and that utility workers would need at least the weekend, if not longer, to finish restoring power.

Forecasters said the subfreezing conditions were expected to persist across the eastern U.S. into February. The National Weather Service said chances of additional, significant snowfall were low in places such as Nashville, but said weekend temperatures would reach dangerously low single digits with wind chills below zero, and it cited a growing chance of heavy snow in the Carolinas and Virginia.

Mississippi officials said passenger vehicles were cleared from the frozen highways by about 3 a.m. Wednesday, according to the Mississippi Department of Public Safety, though long lines of commercial trucks still remained awaiting removal hours later. In communities along the affected routes, local authorities asked residents to help stranded motorists with supplies such as water, food, blankets or gas, as one nearby roadway remained effectively impassable.

In Red Banks, Mississippi, Lacey Clancy said the highway looked “like a parking lot” and that many people had run out of gas, abandoning their vehicles. Angie Gresham, who lives in Holly Springs, said hundreds of stranded vehicles lined Interstates and local streets, and that stranded truck drivers were searching for stores and restaurants that still had power while others simply tried to survive the cold.