PORT HARCOURT, Nigeria, May 24 (Reuters) - Unidentified gunmen shot and killed two people when they opened fire on a crowd at a bus station in Nigeria's southern city of Port Harcourt, witnesses said.

They said several other people were wounded in the shooting, the latest example of violence in Nigeria's lawless oil region, where attacks on Western facilities, kidnapping of foreigners and gang violence have been on the rise since last year.

"We have so far received 13 persons with serious gunshot wounds. Two of them have died, while some of them are still in critical condition," said a worker at Teme Hospital in Port Harcourt, who asked not to be named because he is not authorised to speak to the media.

The gunmen were in three vehicles moving around the central area of the city. At the Mile One bus station, they shot into the crowd, hitting one woman in the buttocks and another in the ribs. A bus conductor was shot through the forehead.

Local human rights activists said the attack was probably linked to infighting in the Rivers State chapter of the ruling People's Democratic Party, which won last month's election amid massive rigging, according to international observers.

Military helicopters flew over the city as police pursued the gunmen, witnesses said.

Violence over the past 18 months has forced thousands of foreign workers to flee the Niger Delta, a maze of mangrove-lined creeks that is home to all of Nigeria's oil wealth, and shut down about a third of the nation's capacity.

There are currently 15 foreign hostages being held by various armed groups.

Some of the groups behind the violence in the region have made political demands, but the line between militancy and crime is blurred.

Poverty and endemic corruption in government is at the root of the worsening insecurity in the delta, where impoverished fishing villages host Africa's biggest oil industry.

AlertNet news is provided by