KAMPALA (Reuters) - A fight erupted in a refugee camp in Uganda during a World Cup soccer match and four people were killed, police said, adding they have arrested 15 refugees from South Sudan in connection with the bloodshed.

Uganda is host to an estimated 1.4 million refugees, including more than a million from South Sudan where a five-year-old civil has killed tens of thousands and uprooted an estimated quarter of the population of 12 million.

Fighting in South Sudan has increasingly followed ethnic lines.

The violence took place in a camp in West Nile region on Sunday during a match between Brazil and Switzerland, said Deputy Police Spokesman Patrick Onyango, with refugees from the Nuer ethnic group battling rival ethnic Dinka.

The trouble began at half time when a Dinka man, identified as Thon Majok, left the video hall, only to find when he came back that a Nuer man had occupied his seat.

“Majok ordered the Nuer man to vacate the seat. The Nuer man declined. The two started fighting then each was joined by his tribesmen,” Onyango said by phone late on Thursday.

A 13-year old boy was among the dead.

Police had arrested 15 suspects in connection the killing of the four and the injuring of several people, he said.

“The security situation in the South Sudanese-dominated refugee camps has stabilized,” he said.

Authorities had decided to separate refugees from the two ethnic groups and keep them in different camps, he said.