A fire allegedly set during an attempted jailbreak from Venezuelan police holding cells killed 68 people on Wednesday, the country's top prosecutor and an inmates' rights group said.
The blaze at the detention facility in Carabobo state is the latest in a series of deadly incidents in Venezuela's overcrowded jails.
"In light of the terrible events that took place in the Carabobo state police headquarters, where 68 people died in a presumed fire, we have appointed four prosecutors … to clarify these dramatic events," chief prosecutor Tarek William Saab said on Twitter.
Carlos Nieto, head of Una Ventana a la Libertad (A Window on Freedom), said that "some burnt to death and others asphyxiated" after setting fire to mattresses and stealing a guard's gun in an attempt to break out.
The dead included two women thought to have been visiting the jail at the time of the incident, Mr Nieto said.
Rafael Lacava, the governor of Carabobo state, expressed his "consternation" over the events but did not provide a toll.
"A serious and profound investigation has been initiated to find the causes and those responsible for these regrettable events," he said on Twitter, expressing solidarity with relatives of those who died.
Relatives of those being kept in the detention centre tried to force their way into Carabobo state police headquarters. After one officer was injured by a stone, the crowd was dispersed by police firing tear gas.
A video posted on Twitter showed dozens of people demanding information in front of police guarding the site.
"I am a desperate mother. My son has been here a week. They have not given any information," Dora Blanco told local media.
Venezuela's prisons suffer from dire overcrowding and a shortage of basic supplies, struggling under the deepening economic crisis that is gripping the once-wealthy oil-producing country.
Because of the lack of space in penitentiaries, convicts are often sent to police holding cells like the ones in Carabobo, meant to be used as temporary pens for suspects facing charges or court hearings, where detainees are supposed to spend a maximum of 48 hours.
Mr Nieto's association estimated that the temporary detention centres were overfilled by five times their capacity.
"All the police stations in Venezuela are facing similar or worse conditions of overcrowding, lack of food and disease," he said.
The association said 65 people died last year in the holding cells due to violence, malnutrition or tuberculosis.
Two weeks ago, 58 detainees escaped holding cells on Margarita Island, a favoured tourist spot, when a hole opened up in their facility's wall. They were all soon recaptured.
In August 2017, a riot left 37 dead and 14 wounded in police cells in the southern state of Amazonas, while an April 2017 clash between rival gangs left 12 dead and 11 injured in the Puente Ayala prison in the eastern city of Barcelona.
A month before that, the remains of 14 people were found in a mass grave in the General Penitentiary of Venezuela, in San Juan de Los Morros in the country's centre.