She said many prisoners were being moved to El Rodeo I prison east of Caracas. That prison was the scene of clashes and a 27-day standoff last year pitting armed inmates against troops. Officials say the prison has been partially rebuilt after some areas were destroyed by fire during the violence and walls were knocked down by authorities searching for hidden weapons and other contraband.
Violence is common inside Venezuela's severely crowded prisons, where inmates often manage to obtain weapons and drugs with the help of corrupt guards. The watchdog group Venezuelan Prisons Observatory says about 560 people died in Venezuelan prisons last year, up from 476 in 2010.
Before the violence died down on Thursday, skirmishes erupted outside the prison between distraught relatives of inmates and troops using tear gas to drive them away.
Tensions at La Planta prison have grown since April 27, when Varela said authorities found a tunnel dug by inmates that led to a sewer, foiling an escape attempt. Three days later, gunfire erupted at the prison after what Varela described as another escape attempt.
In a May 8 incident, heavy gunfire rang out at the prison and one man in a nearby apartment was killed by a stray bullet.
Associated Press writers Jorge Rueda and Christopher Toothaker contributed to this report.