Crossfire broke out in Uribana prison outside Barquisimeto in Lara state after some prisoners resisted a spot check on weapons at the prison.
Explosions were heard near the prison, which currently jails 2,600 inmates, official records show.
Nineteen ambulances arrived at the scene, and a priest and a soldier were among the dead.
The Venezuelan government has not yet made any comments on the revolt, one of the most violent incidents in the country.
Venezuela is one of the most violent countries in Latin America. More than 21,000 murders were registered in the country in 2012, up 15 percent from the previous year, according to international organizations. National murder rate has reached 73 per 100,000 inhabitants.