Powerful storms stretching from the U.S. Gulf Coast to the Great Lakes in the north wrecked two small towns and killed at least 28 people as the system tore roofs off schools and homes and damaged a maximum security prison. It was the second deadly tornado outbreak this week. At least 28 people were killed, including 14 in Indiana and 12 in Kentucky, authorities said. In Indiana, Marysville was leveled and nearby Henryville also suffered extreme damage. Each is home to about 2,000 people. "Marysville is completely gone," said Clark County Sheriff's Department Maj. Chuck Adams. Aerial footage from a TV news helicopter flying over Henryville showed numerous wrecked houses, some with their roofs torn off and many surrounded by debris. The video shot by WLKY in Louisville, Kentucky, also shows a mangled school bus protruding from the side of a one-story building and dozens of overturned semitrailers strewn around the smashed remains of a truck stop. An Associated Press reporter in Henryville said the high school was destroyed and the second floor had been ripped off the middle school next door. Classroom chairs were scattered on the ground outside, trees were uprooted and cars had huge dents from baseball-sized hail. Authorities said school was in session when the tornado hit, but there were only minor injuries there. Afterward, volunteers pushed shopping carts full of water and food up the street and handed it out to people. The rural town about is the home of Indiana's oldest state forest and the birthplace of Kentucky Fried Chicken founder Col. Harland Sanders. Ernie Hall, 68, weathered the tornado inside his tiny home near the high school. Hall says he saw the twister coming down the road toward his house, whipping up debris in its path. He and his wife ran into an interior room and used a mattress to block the door as the tornado struck. It destroyed his car and blew out the picture window overlooking his porch. "There was no mistaking what it was," he said. The powerful storm system was also causing problems in states far to the south, including Alabama and Tennessee where dozens of houses were also damaged. The threat of tornadoes was expected to last until late Friday. The outbreak comes two days after an earlier round of storms killed 13 people in the Midwest and South. At least 20 homes were badly damaged and six people were hospitalized in the Chattanooga, Tennessee, area after strong winds and hail lashed the area. In Cleveland, another Tennessee town, Blaine Lawson and his wife Billie were watching the weather when the power went out. Just as they began to seek shelter, strong winds ripped the roof off their home. Neither were hurt. "It just hit all at once," said Blaine Lawson, 76. "Didn't have no warning really. The roof, insulation and everything started coming down on us. It just happened so fast that I didn't know what to do. I was going to head to the closet but there was just no way. It just got us." Thousands of schoolchildren in several states were sent home as a precaution, and several Kentucky universities were closed. The Huntsville, Alabama, mayor said students in area schools sheltered in hallways as severe weather passed in the morning. An apparent tornado also damaged a state maximum security prison about 10 miles (16 kilometers) from Huntsville, but none of the facility's approximately 2,100 inmates escaped. Alabama Department of Corrections spokesman Brian Corbett said there were no reports of injuries, but the roof was damaged on two large prison dormitories that each hold about 250 men. In California, a late winter storm that dumped at least 6 feet (1.8 meters) of snow in parts of the Sierra Nevada mountains created ripe conditions Friday for snow sports enthusiasts but also posed avalanche dangers, as one man died while skiing in back country. Contributing to this report were Associated Press writers Jim Suhr in Harrisburg, Illinois, and Jeff Martin in Atlanta, Associated Press videojournalist Robert Ray in Cleveland, Tennessee, and AP Radio's Shelly Adler in Washington.