ONITSHA, Nigeria (Reuters) - Police in Nigeria s southern Delta state said they killed one suspect and arrested two others accused of involvement in the kidnapping last month of four Britons.  Three of the British hostages, who were taken by gunmen on Oct. 13, were released earlier this week after negotiations, but a fourth, Ian Squire was killed.  Delta state police spokesman Andrew Aniamaka said officers arrested two suspects and killed a third after he opened fire, wounding two officers.  Aniamaka said two other suspects who were arrested previously led police to the three men. Kidnapping for ransom is common in parts of Nigeria, including the Delta region that produces the bulk of the country s crude oil, but is mired in poverty and plagued by criminal and militant activity.  