With the search and rescue operation now winding down, the authorities in West are focusing on ensuring there are no hazardous chemicals remaining on the site, which could be a threat to the public. They are also trying to establish exactly what caused the fire and the explosion that followed it. There is little left of the factory or dozens of houses that bore the brunt of the blast. Police are expected to start allowing residents back into the restricted area in the next 24 hours so people can see what's left of their homes and possessions.