Pretoria authorities have arrested two individuals in connection with one of the two shootings that plunged South Africa into mourning over the weekend.

A total of 19 people died after unknown assailants opened fire on Saturday night, apparently at random, on the patrons of two bars, one in Soweto, a suburb of Johannesburg (15 dead), the other in Pietermaritzburg, in Zulu country, in the east (4 dead).

In a statement announcing the two arrests without further details, the Ministry of Home Affairs said it was a “first step towards holding to account all those who organised the country’s deadliest weekend”.

A spokeswoman for the ministry, Lirandzu Themba, told AFP that the police believe the two people arrested are “linked” to the Pietermaritzburg killing, which was reportedly carried out by two men.

The Soweto shooting was committed by “several gunmen” armed with AK-47 assault rifles, according to the preliminary investigation.

Shootings are common in South Africa, one of the world’s most violent countries, fuelled by gang violence and alcohol, but the indiscriminate nature of the two-weekend killings is baffling investigators.

The violent deaths are “unacceptable and disturbing” and “we cannot allow violent criminals to terrorise us in this way,” South African President Cyril Ramaphosa said in a statement Sunday.