SYOSSET - An explosion destroyed a Syosset home this morning, sending one person to the hospital and leaving his family homeless. Police say 48-year-old Brian Welsh, the owner of the home at 6 Alexander Drive, was apparently in the basement doing some spring cleaning when the blast happened, blowing up the roof and causing the floor to collapse. The explosion could be felt and heard throughout the neighborhood."It almost sounded like a huge container dropped," says neighbor Harvey Kirschner. Welsh was taken to Nassau University Medical Center with severe burns to his body. He was discovered on the front lawn by a LIPA employee who happened to be working nearby and heard the blast.Police are still not sure what caused the explosion, but say it appears to have happened inside the home.