More than 250 people have been arrested in Zambia's capital, Lusaka, to curb xenophobic violence which has hit the city, police say.
At least 62 Rwandan-owned shops have been looted in the the riots which have spread to nine poor neighbourhoods, police added.
Many Zambians describe it as the worst xenophobic violence in the country.
The riots started in two areas on Monday following rumours that Rwandans were behind ritual killings in Lusaka.
At least seven people have been murdered in recent weeks and their body parts removed.
Rumours circulating on social media alleged the body parts would be used as charms to ensure success in business.
Riot police have been deployed to quell the unrest, and many Rwandans have fled to police stations to take shelter, reports the BBC's Meluse Kapatamoyo from Lusaka.
The riots have shocked many Zambians who say they cannot recall such hostility towards foreigners in the country, she adds.
Rwandans are the largest group of immigrants in Zambia, owning shops in the densely populated areas which have been affected by the riots.
They number about 6,000, and many of them came to Zambia as refugees fleeing the 1994 genocide in their home country.
Young men have been ransacking their shops, possibly reflecting growing frustration at the high levels of unemployment and the rising cost of living, our correspondent adds.
Speaking after visiting some of the riot-hit areas, Home Affairs Minister Davis Mwila said 11 people had been detained on suspicion of being involved in ritual killings, Reuters news agency reports.
The riots were triggered by the "false" rumour that police had released a "suspected foreign ritual killer", Mr Mwila said, in an earlier statement.
"The anti-social and criminal conduct seen in the high density areas north and west of the city of Lusaka must come to an immediate end," he added.