In the United States, four people were killed, roofs were ripped from homes and churches, and trees were torn from the earth yesterday when a tornado hitting in the dark of night ripped through a region in southern Mississippi. <br/><br/>Officials said four people died after the twister blew through the city and surrounding area. The twister was part of a wall of stormy weather traveling across the region, bringing with it rain and unstable conditions. <br/><br/>Authorities have not yet released the names of the four people who died. The search for the dead and injured continued.<br/>'<br/>More than 40 firefighters from across Mississippi had gathered outside Hattiesburg police headquarters to search. <br/><br/>Equipped with dogs and all-terrain vehicles, they were planning on doing a grid search from police headquarters to nearby William Carey University in one of the most heavily damaged areas.