Johannesburg - Parliament's police portfolio committee expressed concern on Wednesday about the shooting in the Pretoria Magistrate's Court.
"The committee wants to know how and where the two suspects managed to get hold of a gun while kept in a holding cell," chairperson Francois Beukman said in a statement.
It was worrying to see there were still unaccounted for guns in South Africa, he said.
Two awaiting-trial prisoners opened fire in the court on Tuesday, grazing a court orderly's back and shooting a police officer in the head.
The Times named them as Sergeant Theopilus Mogafe, the court orderly, and Constable Eddie Ngobeni. Ngobeni was apparently trying to save Mogafe when he was shot.
The two prisoners, robbery accused Lucky Segwape, 28, and Nthabeleng Matlatfi, 26, were due to appear in court on charges of house robbery and possession of unlicensed firearms. They emerged from the holding cells and opened fire in the courtroom.
Ngobeni was due to testify in their case. It was unclear how they got the weapon.
The two fled the court and hijacked a car outside. The vehicle was abandoned in Atteridgeville, where they hijacked another car, a red VW Polo.
The two had not been arrested yet. Police were also searching for a third man who escaped from custody during the shooting.
Beukman said the owner of the gun used in the attack needed to be investigated. If it turned out to be a police officer, SAPS internal processes and criminal proceedings needed to be instituted.