A powerful but short-lived tornado ripped through a small town in eastern Mississippi yesterday afternoon, tearing the roofs off a Wal-Mart full of holiday shoppers and a La-Z-Boy factory and injuring at least 60 people, two of them critically, the authorities said.

The tornado struck about 1:15 Central Standard Time, in Newton, Miss., a city of 3,700 people about 30 miles west of Meridian on Interstate 20 and 60 miles east of Jackson, the state capital. It lasted five minutes, officials said. An 18-wheel diesel tanker was blown off the highway, and the oil spill forced the closing of the interstate, a major east-west artery through the Deep South, for much of the afternoon, said Amy Carruth, spokeswoman for the Mississippi Emergency Management Agency.

Witnesses said a Sonic hamburger drive-in and a Subway sandwich shop were flattened. A nursing home near the Wal-Mart was damaged somewhat, but no patients were hurt, Carruth said. Two supermarkets, a feed store and a fire station were also damaged. But Carruth had no information on the number of homes damaged or destroyed.

"I was fixing to go home, and sitting in the front of the store," said Wanda Brown, a Sonic employee. The lights blinked off, on and off again, she said, when she saw a woman trying to pull the door shut. "The wind pulled the door off. We took off running to the back and went into the cooler."

Nathan Cumberland, 25, was shopping in the Wal-Mart when, he said, "it turned real black, the windows busted and the roof started peeling off." He said he ran to the back of store and "just laid in the aisle. The roof peeled off over me, and I could see sky."

Dr. Razee Ahmad, an emergency room physician at Newton Regional Hospital, said 60 people were treated there, and 12 were taken to Meridian for more serious injuries, mostly cuts from flying glass. Carruth said the two people listed in critical condition had suffered neck injuries.

Gov. Ronnie Musgrove declared a state of emergency after the tornado left about 6,800 people without electricity. Telephone and cellular service was also down, Carruth said. Musgrove and the state emergency management director inspected the scene early last night, and a damage assessment team from the National Weather Service began work at sunset.

Carruth said conditions had been ripe for tornadoes, and a tornado watch was in effect for the Newton area when it hit.

Jim Butch, a meteorologist at the National Weather Service in Jackson, said the storm system had first emerged Wednesday and affected Louisiana, Arkansas and East Texas. It slowed down overnight, but by yesterday an upper-level system of cold air had begun pushing a warm front through the area, creating a rotating storm.