JOHANNESBURG (AP) — South Africans on Wednesday expressed shock over the murder of two toddlers whose bodies were found in a township toilet, prompting angry protests from residents who looted shops and burned tires in the street.

Police were holding several people for questioning about the deaths of the girls, who were two and three years old and were discovered Tuesday in the Diepsloot area north of Johannesburg after being reported missing on the weekend.

In a separate incident, South African media reported that two other toddlers were found dead in Katlehong, east of Johannesburg. Police suspect they were poisoned.

The killings in Diepsloot fueled angry accusations from residents that police were failing to provide security. Local media said some immigrant-owned shops were attacked, exposing tensions between local community members and residents from other African countries in poor areas of South Africa where there are few opportunities.

Nathi Mthethwa, South Africa's minister of police, urged communities to help police solve crimes such as the killing of the children, saying the government would not tolerate lawlessness in the street.

"We condemn any form of mob justice," he said. "Destroying property, looting shops, cannot be a legitimate form of resolving challenges around policing. "

Diepsloot was quiet on Wednesday.

"These gruesome incidents of extreme torture and murder of our children do not belong to the society that we are continuously striving to build together," President Jacob Zuma said in a statement.

Police are investigating whether the Diepsloot killings are linked to the death of a 5-year-old girl in the same area in September, the South African Press Association reported. Police suspected she had been sexually violated and strangled.