MEXICO CITY — With little interference from guards, the inmates rampage.

Video images capture dozens of prisoners racing over fences, pummeling one another, breaking windows and furniture and wheeling bodies stacked on a cart.

Guards are there, but do little more than watch as inmates force open gates and stroll through corridors en masse. Later, the guards can be seen dragging the wounded, and several apparently dead prisoners, into a room.

After the riot, at a prison in San Luis Potosí State in central Mexico two years ago, the authorities said 13 people had been killed and 65 wounded.

Now the video footage, recorded by security cameras at the time of the riot, is providing a vivid illustration of what actually happened inside the prison, raising tough questions about the response to such outbreaks in the country’s chronically overcrowded and violent prisons.