WINDHOEK, Namibia—Thirteen members of the same family have died in Namibia after eating porridge that authorities believe became toxic when it was mixed with a fermented substance left over from a homemade alcoholic beverage, the state broadcaster reported.

The Namibian Broadcasting Corporation said another four people are in a criticial condition in the hospital. NBC, quoting the Namibian health ministry, said at least 20 people consumed the “poisonous or toxic” porridge after it was mixed with sediment from a homemade beer.

The victims ranged in age from 2 to 33, NBC said.

The incident happened in the Kavango East region in the far northeast of the country.