JOHANNESBURG, South Africa -- Police in South Africa say they've arrested three men -- including a game ranger -- they suspect shot seven rhinoceros to death and dehorned them.

Capt. Paul Ramaloko of the South African Police Service said Tuesday the men had been arrested that morning on suspicion of killing the rhinos in the country's Northwest province. He said the accused would appear in a magistrate court Thursday.

The rhinos were killed this weekend at a game farm near Rustenburg, a city about 100 kilometres northwest of Johannesburg.

With these killings, South Africa's Department of Environmental Affairs said 570 rhinos had been hunted illegally and killed this year alone. South Africa is home to some 20,000 rhinos. Growing Asian demand for rhino horn is believed to be behind the poaching spike.