In the wake of the 2011 Joplin tornado in which seven people were killed in a Home Depot when the panel walls collapsed after the store was hit by an EF5 tornado, engineers in an article published in "The Kansas City Star" criticized the practice. They said that once one wall falls, it creates a domino effect. Twenty-eight people in an un-reinforced training room in the back of the building survived. According to a study of the collapse, the tornado hit the south corner of the store and lifted the roof up causing the west walls to collapse into the store. The walls on the east side (where the people survived) collapsed out. Only two walls remained standing. Engineers said that stronger roof-to-wall connections might have tempered the collapse. Two other big box stores at the corner that had concrete block construction (an Academy Sports + Outdoors and Walmart) lost their roofs but the walls remained intact. Those buildings were not directly hit by the tornado but the Home Depot building suffered a direct hit. Three people died in the Walmart, but 200 survived. The engineers told the Star that when concrete blocks fail they usually break apart, and do not come down in huge slabs. Home Depot, which has hundreds of stores built with tilt-up, said it disagreed with the finding and that it would use tilt-up when it rebuilt the Joplin store.