Grieving storm survivors turned to prayer and the good grace of volunteers Sunday across the US south as shattered communities looked to rebuild from the second-worst tornado disaster on record. Churches from Mississippi to Virginia flung open their doors for prayers, some in the very houses of worship destroyed by powerful tornadoes that claimed nearly 350 lives on Wednesday. \"This is the Bible Belt. Church goes on regardless,\" Tennessee Emergency Management Agency spokesman Jeremy Heidt told AFP. In hardest-hit Alabama, where Governor Robert Bentley declared a state-wide day of prayer, the faithful gathered under open skies, in parking lots and church sites on the first Sunday since the historic disaster wiped several of their churches off the map.   In the town of Phil Campbell, congregants erected a makeshift wooden cross and sang hymns on the concrete slab where the Church of God once stood, before some of the most powerful tornadoes on record left it and thousands of homes and businesses in splinters. \"Today, we will pray for the people affected by this tragedy and for you that have lost your church. And we ask you: don\'t give up,\" Pastor Keith Pugh told his congregants. The faithful sang and prayed while holding hands, then embraced each other after the service. They had gathered in a neighboring town after the tornadoes completely leveled their Open Door Baptist Church in Tuscaloosa. In the devastated town of Smithville, Mississippi -- population 900 -- the Church of Christ has been converted into a food, clothing and medicine distribution center, and the congregation gathered outside for a short open-air service. \"We\'re just going to remember the dead and buried by taking the Lord\'s supper, and give of our means. People come together when the need arises,\" said church elder Danny Stephenson, 62. \"Of our six churches, four of them is gone,\" he said. \"There ain\'t nothing left. Just wiped clean, like you took a bulldozer to it all.\" Like other communities across the battered region, neighbors helped neighbors, and volunteers conducted search and rescue, cooked meals for victims, and helped haul debris. \"The whole town has come together,\" Stephenson said. \"And I\'ve talked to one family, they\'re going to rebuild right where they\'re at.\" President Barack Obama on Sunday declared a major disaster in Tennessee, to allow for federal aid to the state following disaster declarations for Alabama and parts of Georgia and Mississippi. He dispatched cabinet members to tour the destruction in Birmingham, Alabama, where they spoke with survivors and assured expanded federal aid to help communities recover and rebuild. Homeland Security Secretary Janet Napolitano pledged the federal government would continue to support the stricken states, helping them \"come to grips and recover from this really terrible swath of tornadoes that swept through the south.\" \"That makes the sense of urgency for us even more acute when we see the type of damage we are seeing here today and the spirit of the people,\" she told reporters in Smithville. Parts of the south were bracing for another beating after tornado watches were issued again, this time in Texas, Arkansas and Oklahoma, though forecasters warned any new storms were unlikely to be as devastating. The American Red Cross has opened 16 shelters across Alabama, taking in about 900 of the newly homeless, the organization announced. Obama reiterated his pledge to help the region recover. The scope of the devastation was almost unimaginable, particularly in Tuscaloosa, where Mayor Walter Maddox said 5,731 building have been destroyed or badly damaged and more than 400 people remained unaccounted for, although he acknowledged several of those were likely staying with relatives. Alabama was worst hit, with 250 people killed and 2,219 injured. Mississippi has confirmed 35 deaths, and its emergency management agency touched on the scope of the disaster in reporting 993 homes destroyed and another 2,527 damaged in the state. There were also 34 deaths in Tennessee, 15 in Georgia, eight in Arkansas and five in Virginia. The overall death toll of 347 is exceeded only by a tornado outbreak in March 1925 that left 747 people dead. Fire and rescue teams were going door to door, some with cadaver dogs, in the poor Tuscaloosa neighborhood of Alberta City, where blocks of low-income housing were left in ruins and residents were seen painstakingly combing through the rubble.