This disclosure comes on the eve of the TRC's two-day event hearing in Athlone, Cape Town, on the police ambush in which three people, including two children, were killed.
"The investigative unit has numerous documents in its possession which throw new light on the incident," TRC spokeswoman Christelle Terreblanche told Sapa on Monday.
She said eye witnesses to the shootings and relatives of the three victims were among 11 witnesses due to give evidence on Tuesday, the first day of the hearings.
Michael Miranda, 11, Jonathan Claasen, 21 and Shaun Magmoed, 16, were killed on October 15, 1985 when security force members hiding in wooden crates on the back of a truck opened fire on a group of alleged stone-throwers.
The incident caused an international outcry but police defended the ambush, saying it was a necessary technique to protect the public from stone-throwers.
Terreblanche said four minutes of film footage shot by a CBS film crew that witnessed the shootings would be screened on the second day of the hearings.
The footage is expected to be followed by the testimony of seven security force members subpoenaed by the TRC in connection with the incident.
All but one are former or serving policemen. The seventh is a serving member of the SA National Defence Force, Lt-Col Salmon Pienaar, a former officer commanding of SADF personnel on the Cape Flats.
Terreblanche named the six policemen as Dir Christian Loedolf, a former commander of the SA Railway Police's regional unrest task force, Insp Andrew Smit, Sgt Alexander Rossell, Sgt Albertus Smit, Sgt Frank van Niekerk and Lt Douw Vermeulen.
Although a 1989 inquest found that police had been negligent in causing the youths deaths, former Cape Attorney-General Niel Roussouw declined to prosecute, a decision supported by then Justice Minister Kobie Coetsee.
The families of Magmoed and Miranda took the case to court in South Africa's first private prosecution but failed to win a conviction.