A huge explosion at an industrial gas plant in southeastern Nigeria razed nearby buildings and killed several people on Christmas Eve, police said...The blast at the Inter Corp Oil Limited gas plant, a subsidiary of Nigerian conglomerate Chicason Group, started at 1:00 pm on Thursday, swallowing the plant in a fire that gutted surrounding building...[Authorities] could not confirm local reports that more than 50 people were killed, saying an investigation was underway...Nigeria is Africa's largest oil producer...Accidents happen frequently in the country...