Terrifying video shows a Hayward, California, home leveled Thursday by an explosion after contractors allegedly damaged an underground gas line.Six people were injured, including three who were seriously hurt, according to Ryan Ishimoto of the Alameda County Fire Dept. The blast destroyed the Bay Area home and damaged several other properties.RELATED STORY | Ohio explosion caused by crew cutting gas line they thought was turned off, investigators sayAt least one person was inside the home before it was flattened. Miraculously, that person was not injured."It's going to be an extensive investigation, but this was a 3rd party that had dug in," said Tamar Sarkissian, a spokesperson for the Pacific Gas and Electric Company. "We did arrive on the scene shortly after, and we did get to work to isolate the line and to stop the flow of gas." ...read more read less