A possible tornado and other severe storms shattered parts of southern Mississippi early Saturday, killing at least four people and injuring more than 20 others in Forrest, Lamar and Perry counties, the Mississippi Emergency Management Agency said. The National Weather Service office in Jackson dispatched a damage survey team to the area to investigate what was a likely tornado that also damaged buildings in Hattiesburg and Petal, including parts of a college and a fire station, officials said. Preliminary survey finds evidence of tornado that may have been at least EF-3 intensity, weather service said on Twitter. "There are widespread power outages as the tornado ran across three counties lines," said Greg Flynn, spokesman for the Mississippi Emergency Management Agency. Officials warned of downed power lines and debris spread over large areas and urged people to avoid traveling. Gov. Phil Bryant said he has been in regular contact with the emergency agency and "ordered all available resources toward rescue and recovery." "I will travel to the affected areas today to get a full assessment of the damage and the need," Bryant said in a Facebook post. Hattiesburg has taken a lot of damage, the National Weather Service said in an advisory. It's the largest city in Forrest County with about 46,000 people. A search and rescue operation is underway in the city, Mayor Johnny DuPree said before dawn Saturday. A tornado may have caused the damage, CNN affiliate WDAM-TV reported. Most of Hattiesburg's damage appeared to be on the downtown's outskirts, DuPree said. A fire station was damaged, as were parts of William Carey University, a private Christian college with about 4,000 students. Students at William Carey were reporting minor injuries, the university said. Dormitories and other buildings were damaged, the school said. "Officials working to ensure students are safe. Some students reporting minor injuries. Damage to dorms, Tatum Court, Thomas Hall," the university said on Twitter. Volunteers began cleaning up the damage Saturday afternoon. Windows were blown out and roofs of buildings peeled back at the Hattiesburg Salvation Army, WDAM reported. WDAM reporters and editors posted to Twitter pictures of severe damage in Hattiesburg and in Petal, an adjacent city of about 10,400 people. Parts of an AT and T store and a loan shop collapsed at a shopping center in Petal, one of the images showed.