Six foreign oil workers were kidnapped and a Nigerian sailor was killed when dynamite-wielding gunmen attacked an oil vessel early Tuesday, a navy spokesman said. Capt. Obiora Medani said the sailor was a guard aboard the Chevron Corp. ship, which was attacked off Bayelsa state, in the oil-rich south of the West African country, the Associated Press reported. Medani had no further information on the Tuesday morning attack on FPSO Oloibiri, which is stationed offshore to store crude oil.