The ANC's National Youth Task Team (NYTT) says it's "disturbed and dismayed" at the violence which broke out at a gathering of Youth League members in Hammanskraal on Saturday.
A 25-year-old ANCYL member, identified as Lethabo Nkoana by the NYTT in a statement, was shot and killed, while another member was wounded at the "cadre assembly", one of many called by the the NYTT as it seeks to "communicate the roadmap to congress and to assess the state of the organisation".
The event was held at Temba Stadium.
In its statement, the task team said the assembly was "adjourned as a result of disruptions and, after the adjournment, violence escalated outside the venue of the meeting leading to the killing of a comrade Lethabo Nkoana".
It said its members had visited Nkoana's family on Sunday.
"The NYTT condemns with the strongest terms what transpired in Tshwane as well as all other incidences of violence and disruptions in our meetings," the statement said.
On Saturday evening, Gauteng police spokesperson Brigadier Mathapelo Peters told News24 preliminary findings suggested there was an argument between delegates at the rally before the shooting.
"Preliminary reports reveal that an argument broke out amongst some delegates during a political rally at the stadium, and this led to scenes of violence where the delegates allegedly started attacking each other.
Peters added: "It is reported that the deceased was trying to defuse the fight when an unknown man emerged from the crowd and fired shots at the deceased, fatally wounding the 25-year old victim."
She said the surviving shooting victim was rushed to hospital.
"The suspect is said to have driven off in a grey BMW with unknown registration," Peters said.
ANCYL Tshwane regional chairperson Lesego Makhubela told News24 those who witnessed the shooting would assist police.
The shooter was apparently known to witnesses and was not an ANCYL member, Makhubela said.