FOUR people died, several were injured and property was wrecked in a explosion at a gas site near Port Harcourt in eastern Nigeria, the contractor at the site said on Monday. The blast occurred at the Obite plant construction site on Saturday when a welding gas cylinder exploded. The gas site is a major facility of Elf Petroleum designated as one of the plants to supply natural gas to Nigeria’s Liquefied Natural Gas operations.A sub-contractor to Elf at the site, Ponticelli Nigeria, said that property within a radius of 300m of the site was destroyed in the explosion.