How do natural gas explosions happen? Investigators probe origin of Harford County blast

All it takes is gas and a spark. Fire safety experts say the aftermath of an explosion in Harford County shows the magnitude of what gas leaks can do: A Bel Air residence was leveled, killing both the homeowner and a Baltimore Gas and Electric Co. contractor. The blast also spread debris throughout Arthurs Woods Drive and rendered 16 homes uninhabitable.