Officials in South Sudan say more than 20 people have been killed in clashes triggered by cattle rustling, including medical workers slaughtered in a rampage by security forces.

Officials said the killings began after raiders stole at least 750 cattle last weekend.

Felix Otuduha, a spokesman for Eastern Equatoria state, said Thursday that seven security forces, five cattle rustlers and two civilians died in a clash Monday.

Following that clash, the government sent 150 soldiers and police after the cattle raiders. David Mayo Nailo, a member of parliament, said the security forces, enraged by the thefts and violence, attacked a hospital, killing four medical staff and a patient. He said the soldiers then set fire to the hospital.

Most of South Sudan's internal clashes take place between rival tribes.