Unidentified gunmen have blown up a pipeline in Nigeria's oil-producing Niger Delta region, officials say.
Nigeria's oil pipelines are often cut by thieves, leading to explosions
Eight people have been killed and many more are missing after the pipeline was destroyed with dynamite, said the chairman of the local authority.
Oil company Shell said it had shut down two wells supplying the pipeline.
Nigeria is Africa's major oil producer but Niger Delta residents say they have not benefited from their oil wealth. Youths often target oil installations.
Pipelines are frequently cut by thieves to siphon off the oil. These have often exploded, killing hundreds of people over the years.
Andoni local government area chairman Monwan Etete said that youths in four speed-boats had warned residents of local fishing villages to leave their homes on Monday night - shortly before the attack.
He said that 21 villages had been affected and that a huge fire was still raging.
He said some of those killed were children.
The blast occurred 50km west of the oil centre of Port Harcourt, Shell said.
Shell said the fire may have been caused by a dynamite attack by unknown persons.
Production has been cut by 170,000 barrels a day - 7% of Nigeria's normal output.
Mr Etete said he thought a local militia - the Niger Delta People's Volunteer Force - may be behind the attacks.
The NDPVF say it wants independence for the region. Its leader Mujahid Dokubo-Asari is in prison on treason charges.
Shell says there have been two other attacks nearby.