By Alex Last
BBC News, Port Harcourt
The Nigerian army has launched an operation against a suspected criminal hideout close to the oil city of Port Harcourt in the Niger Delta.
Militants and gangs have made Port Harcourt a violent place
An spokesman said troops and helicopter gunships were used.
They targeted a gang suspected of killing three local chiefs and two others in the Obogoro community.
In the last month, the army and the local authorities have pledged to destroy armed gangs that have been operating in Port Harcourt.
From mid-morning on Friday, trucks loaded with soldiers backed up by helicopter gunships moved into the Obogoro waterside community on the outskirts of Port Harcourt.
The army said its mission was to deal with an armed gang, hiding out in the nearby forests, which was suspected of being behind the murder of three local chiefs from the community.
The army said it fired on the suspected hideout from land and air, but declined to comment on the number of casualties.
It is all part of a new policy to use the military to crush the region's powerful armed gangs.
Ostensibly, the policy followed a turf war between two major gangs - known as "cults" - fought out on the streets of Port Harcourt in August.
Many were left dead and many more injured in the fighting.
The state government said it would not stop until the criminal gangs were destroyed.
But politicians and gangs here have had a long, close relationship.
In the past, the gangs have been paid to keep things quiet or to help ensure victory in rigged elections.
It seems that somewhere along the line, following April's general elections, this arrangement has broken down.
But despite all the current military bluster, there are those who wonder whether anything has really changed.
Civil rights activists say if the government were serious, both the gang leaders and, more importantly, their political sponsors would be brought to book.