CARACAS (Reuters) - Nine prisoners and two guards were killed during a riot in a prison in the western Venezuelan state of Lara, Prisons Minister Iris Varela said on Friday, the country’s second in a week.

The latest riot at the Fenix prison on Thursday was now under control and would be investigated by the prosecutor’s office, Varela said.

On Wednesday, inmates rioted at the Helicoide prison complex in Caracas, where several prominent opponents of President Nicolas Maduro’s socialist government are detained. No one died in that incident.

Varela said that Joshua Holt, a U.S. citizen and Mormon missionary who jailed in the Helicoide, was still incarcerated. The Helicoide revolt prompted the U.S. government to call for his release.

A U.S. citizen was also being held at the Fenix prison, officials from the U.S. embassy in Caracas told a news conference, adding that they were concerned for his safety.

Weapons and drugs are rife in Venezuela’s infamous prisons.