Officials in Mexico say at least 27 people have been killed and 52 injured in a big explosion at an oil pipeline in Puebla in the centre of the country after thieves tried to siphon off oil from the pipeline which belongs to the State oil company Pemex. The explosion sent rivers of burning oil through the streets, destroying homes and cars and forcing hundreds of people to flee. Mexican President Felipe Calderon has promised to launch an investigation. Puebla State Secretary Valentin Meneses said the explosion injured 52 people as well as destroying 32 houses and damaging scores more in San Martin Texmelucan – a small community about 80 kms east of Mexico City. He said that according to early indications, a criminal gang had punctured the pipeline.The fire was brought under control by midday, and the state oil monopoly Pemex said it had shut the pipeline down.