Gunmen in speedboats attacked two oil services ships and kidnapped at least two Russians in separate incidents in Nigeria's Niger Delta, a security contractor working in the oil industry said on Saturday. The Falcon Crest and Falcon Wings were attacked late on Friday off the coast of southern Nigeria's Akwa Ibom state near crude oil facilities operated by Canada's Addax Petroleum, the security source said, adding a Filipino captain on one of the vessels was killed.