GATESVILLE, Texas (KTRK) -- Authorities say one person is dead and 12 people were injured in an explosion at a Texas hospital.The Gatesville Police Department confirmed an explosion erupted at Coryell Memorial Hospital on Tuesday afternoon.The victims in the blast are all construction workers, according to police. No patients were injured in the blast.Eyewitness video shows thick smoke pouring from the building as medical workers and emergency personnel evacuate patients from the hospital.The cause of the explosion was not immediately known.Gatesville is a town of nearly 12,500 people, located about 130 miles southwest of Dallas.