At least two football fans died and several others injured in a stampede at FNB stadium in Johannesburg on Saturday, said police and officials.

A man injured in a stampede at South Africa's FNB Stadium is loaded onto an ambulance by paramedics in Soweto, Johannesburg, South Africa, July 29, 2017. /Reuters Photo‍

The incident occurred at a pre-season local derby between Kaizer Chiefs and Orlando Pirates, the country's most popular teams, both from Soweto, when "a rolling mass of people were trying to get into the stadium," according to police spokeswoman Lorraine van Emmerik.

A man injured in a stampede at South Africa's FNB Stadium is attended to by paramedics in Soweto, Johannesburg, South Africa, July 29, 2017. /Reuters Photo

A witness said that 15 minutes into the match "there was lots of traffic to get inside the stadium... people were getting angry and some were drunk... and wanted to get into the stadium quickly."

In a statement cited by the online football website KickOff, the match sponsors Carling Black Label said they "are saddened by the fatalities that occurred" and that the incident was unexpected "as solid security plans were put in place in conjunction with SAPS and various other stake holders, to ensure that this is a risk-free event."

File photo of the FNB Stadium, in Johannesburg December 7, 2009. /Reuters Photo

The 87,436-seater venue, the largest in South Africa, also hosted the 2010 World Cup final.