(BBC) A foreign oil worker has been killed in an armed attack on a compound in the Nigerian oil city of Port Harcourt.
Police say one Colombian national was killed, while a second Colombian and a Filipino have been kidnapped.
The attack comes days after militants in the Niger Delta called off a ceasefire after their leader's arrest.
In the past, oil workers kidnapped in the Delta have usually been released unharmed. Militants want the region to receive more oil revenues.
Security contractors said about 10 gunmen, some dressed in military fatigues, exchanged fire with soldiers at the Saipem yard before escaping.
"Some armed men came in boats, attacked Aka base where you have Saipem (oil services company)," police spokeswoman Ireju Barasua in Port Harcourt told Reuters news agency.
The main militant group in the region, the Movement for the Emancipation of the Niger Delta (Mend), called off a truce with the Nigerian government on Sunday.
It said it would begin a new campaign of foreign kidnappings after one of its leaders, Henry Okah , was arrested while in Angola.
Mend announced a voluntary truce after the May inauguration of President Umaru Yar'Adua , but says talks have failed.
Previous attacks on oil installations have slashed output of Nigerian crude.
Last week, President Yar'Adua ordered an investigation into alleged links between government officials in the Niger Delta and violent criminal gangs.