The riot was triggered when local media broadcast news that soldiers had been sent to Uribana prison in Barquisimeto to search for weapons, Prisons Minister Iris Varela said.
Hospital director Ruy Medina told AFP news agency that some 90 people were injured, mostly from gunshot wounds.
The dead are thought to include inmates, guards and prison workers.
Note that the riot broke out when soldiers were sent to Uribana prison to search for weapons.