Federal prosecutors in Alaska have charged four men with killing walrus gathered on the state's northwest shore last year, removing the animals' ivory tusks and leaving the meat to waste.

Prosecutors say the four residents of the village of Point Hope twice caused several hundred walrus to stampede, knowing that smaller animals in the herd could be crushed.

A person connected to a remote Air Force radar station in mid-September 2015 photographed 25 dead walrus at Cape Lisburne about 230 miles northeast of the Bering Strait.

Twelve pups were among the dead.

Only Alaska Natives who live in the state may hunt walrus. Prosecutors say all four men were qualified to take marine mammals for subsistence purposes.

Walrus killed only for ivory is considered wasteful and head-hunting is illegal.