Hundreds more are injured.

"If it's found that there's been negligence, a charge of culpable homicide might be opened," Masha said.

The trains were carrying more than 800 passengers when the accident occurred shortly after 10am. The circumstances leading up to the collision are still unclear at the moment.

There are also conflicting reports about the number of deaths, with Masha stating four people had died, while Gauteng Metrorail spokesperson Lillian Mofokeng said the death toll stood at three.

Mofokeng confirmed that over 300 commuters were injured, with 82 suffering had moderate injuries and 159 light injuries.

At around lunchtime, she confirmed that there are two or three people who still trapped inside the trains.

"For now we don't have the full details of what caused the accident," Mofokeng said.

Both trains were from Mabopane station and heading towards Pretoria station.

"Unfortunately one was stationary on the platform when the other one hit it at the back," said Mofokeng.

Fifty ambulances were at the scene and three helicopters assisted with getting critically injured patients to hospitals.

Tshwane Mayor Solly Msimanga said he has always raised concerns about the infrastructure of railway lines and their outdated resources.

"I don't want to speculate about what happened this morning because they are still investigating. But I think there's a need now to immediately have a meeting with Prasa (Passenger Rail Agency of South Africa). We cannot lose any more lives, there needs to be some kind of upgrade in terms of signalling that is in here."

Msimanga said he plans to meet with the families of the deceased.

African News Agency (ANA)