JOHANNESBURG (AP) — A group of Nigerians have boarded a free flight from Johannesburg to Lagos, following a week of violence targeting foreigners in South Africa that stoked tensions between Africa's two largest economies.

It was not immediately clear how many people were on board the flight, operated by private Nigerian airline Air Peace, but Nigeria's government said it estimated 313 people would board.

In total, 640 Nigerians living in South Africa had registered at Nigerian missions to take the flights offered by the airline after bands of South Africans launched violent attacks against foreign-owned shops and stalls, looting and burning the small businesses and attacking some shopkeepers. A second flight leaves later this week.

The violence killed 12 people. Police arrested more than 700 people amid the attacks spread across Gauteng province.