Four people have been sentenced to death in Tanzania for killing an albino because they believed is body parts could be used for magic, police said.

Lucca Haule, assistant commissioner of police, said the four killed a 50-year-old man in Shinyaga, CNN reported. Haule said seven people have been sentenced to hang this year for killing a total of 50 albinos, some of them children.

Franck Alphonse, head of the Tanzania Albino Center, said about 200,000 albinos live in Tanzania. He said the number of killings has risen recently.

"People believe that albino body parts mixed with traditional medicine can make people rich," Alphonse said. "It is a thriving business: Witch doctors are asking business people to bring the body parts of albinos, who are not considered human beings."

The center provides housing and other benefits for albinos, including medicine to prevent skin cancer. Alphonse said many albinos do not go to school because of harassment, leaving them ill-prepared to support themselves.