Authorities in China say they have rescued 30 developmentally disabled children who were being used as slave labor at illegal brick factories.

Some of those rescued from the factories in Henan province have disabilities so severe they cannot tell police where they come from.

Eight people have been arrested in the case, including a 14-year-old factory supervisor.

China suffered a slave labor scandal in 2007, when thousands of people were discovered working without pay in brick factories in Shanxi province.

Despite the government's vow to end the practice, authorities have uncovered several slave labor operations across China since then.