Inmates at a Caracas prison freed the warden and 14 other officers Saturday night after holding them hostage for more than a day.

The prisoners agreed to release their captives after authorities pledged to investigate their complaints that several inmates had been abused, said Nestor Reverol, a deputy justice minister.

"They're with us. They're in good health," Reverol said of the 15 hostages.

The uprising at La Planta prison began at 5 p.m. Friday when inmates clashed with National Guard troops, whom prisoners accused of mistreating a group of inmates as they were being taken to court.

Authorities are investigating that incident, in which four inmates were hospitalized due to injuries suffered while being taken to the courts, Reverol said. Three of the injured inmates later were returned to the prison.

It was unclear how the injuries occurred, and officials did not give details.

After seizing the hostages, the inmates had demanded that their rights be respected and also called for the prison's administrators to be removed. Reverol said there were no plans to dismiss any prison employee, although he added that their conduct would be closely watched.

Inmates' relatives gathered outside the prison during the hostage standoff, and some of them temporarily blocked an adjacent highway to demand action by authorities.

Mayorlet de Santiago, a spokeswoman for relatives of inmates, said: "It can't be that every time they're transferred to court their human rights are violated. They come back beaten."

In a similar incident at another Venezuelan prison earlier this month, inmates took the prison director and others hostage. They released the hostages eight days later after officials agreed to conditions that included dismissing one administrator and providing medical services.

Violence is common in Venezuela's severely crowded prisons, where inmates can obtain firearms and other weapons with the help of corrupt guards.