US police say they have arrested the leader of an armed militia which has occupied a wildlife refuge in Oregon, with one person killed in a shoot-out.

Ammon Bundy and four others were arrested during a traffic stop. One person was injured.

Three others were held in separate incidents.

The militia occupied the refuge this month to support two ranchers jailed for setting fire to federal land.

They say the government has taken land illegally from ranchers for decades.

Other members of the group were reportedly still at the Malheur National Wildlife Refuge in eastern Oregon, where the FBI was setting up a perimeter.