Reports claim 25 people have been killed in riots in an overcrowded Venezuelan prison, which ended with the inmates seizing control.
Sources close to the riots in the Caracas jail said a number of people were wounded and more than 1,000 prison visitors were unable to get out of the building.
The fight started when two rival gangs attacked each other inside the Yare I prison, which was built to house 750 inmates but now holds more than 3,000 prisoners. Firearms were used in the riot.
The violence erupted during visiting hours and more than 1,000 relatives and friends were trapped inside. Prison authorities have confirmed that at least one of the dead was a visitor.
"I saw how they killed my son. It was a disaster; many innocent people who were visiting were killed and injured," said the mother of one victim, Marienca Núñez Ojeda.
"The visit had just started when they began shooting at us - we had to jump in a ditch to find shelter. Several other people who tried to do the same were injured," the father of an inmate told El Nacional.
He managed to escape but his convicted son and his wife and daughter-in-law were trapped inside.
Scores of anxious relatives have refused to move away from outside the building.
Prisons minister Iris Varela said the situation was under control. She added that the authorities planned "to try to impose order" inside the prison.
Those involved in the riots would be punished, she said.
Prison riots are a regular occurrence in Venezuela and many of the 45,000 detainees - nearly four times the original capacity - crowding the country's 33 jails are armed.
The Inter-American Commission on Human Rights said more than 500 people died in 2011 during prison riots across the country. In July a riot at the Cepra penitentiary lasted 20 days, leaving 22 dead.
Two months away from presidential elections, the issue of overcrowded prisons is a sensitive one for President Hugo Chávez, who has promised to modernise the existing infrastructure and build new premises.
"The transformation of the Venezuelan prison system is another big lie that we've been told by this government. How many more will die?" Henrique Capriles, the opposition candidate, said.