State media say police suspect a couple in northwest China poisoned milk from a local farmer, causing three deaths, because of anger over business disputes.
Xinhua News Agency quotes police as saying they found nitrite was added to milk from Ma Wenxuan's farm near the city of Pingliang in Gansu province. Nitrite is an industrial salt that can be poisonous.
Police allege a man surnamed Wu and his wife, surnamed Ma, poisoned the milk because they were angry with the farmer over unresolved business disputes.
A month-old baby and two children younger than 2 died. Another 36 people, mainly children, were sickened.
China has been plagued by a slew of food safety scandals. The government cracked down after a scandal involving the industrial chemical melamine being added to milk products.