An outbreak of violence targeting foreign workers in South Africa has left about 10 people dead and pushed hundreds of others to seek refuge in police stations and churches.
Over the past week, mobs in Johannesburg's townships have been attacking immigrants, who are willing to work for lower wages than many poor South Africans.
Local radio said angry mobs had at first attacked houses owned by immigrants from neighbouring Zimbabwe, Mozambique and other countries in the Alexandra township.
But reports indicated on Sunday that the attacks were spreading across poor townships, as well as to Johannesburg's city centre.
Properties have been looted and destroyed during the week of violence.
"There have been some incidents in the Alexandra area where police opened fire using rubber bullets to disperse crowds," Govindsamy Mariemuthoo, a police spokesman, said on local radio.
The anti-foreigner violence has rattled the authorities and the business community.
The attacks have renewed fears that xenophobia is on the rise.
Mbeki urges action
Thabo Mbeki, South Africa's president, urged police to move quickly to find the instigators.
"It's necessary to move as quickly as possible to establish all the causes and the players in all of this, so that we can then deal with the matter more effectively," he said.
Medical rights group Medecins Sans Frontieres said the situation now amounted to a humanitarian crisis.
"This reminds me of a refugee situation. I have treated bullet wounds, beaten people, rape victims and the people are terrified," Eric Goemaere, spokesman for the group, said.