(CNN) -- Uruguayan officials say they will fully investigate a prison fire early Thursday that killed 12 people and sent eight to the hospital, three of them in critical condition.
In an interview Thursday after touring Rocha Prison in southeastern Uruguay, Interior Minister Eduardo Bonomi said the judge with jurisdiction over the investigation, Vital Rodriguez, will look into complaints that officials were slow to react to the fire.
"It's not up to us to say whether there was a delay or there was no delay," he said in the interview broadcast by CNN affiliate Teledoce TV. "That is up to the judge."
He also noted "the critical situation we have with our prisons," mentioning that the government had previously proposed an emergency law concerning such facilities.
Authorities are offering psychological help, he said, to families of the dead men, other prisoners and police.
In a separate interview broadcast on the same network, Uruguayan President Jose Mujica characterized the fire as "something terrible."
Mujica, a taciturn man who speaks in a low voice, had little to say.
"No matter how much we talk, it won't bring back the people, those young men who remained there," he said.
The fire started around 3:30 a.m. in the prison's Wing No. 2, a news account on the daily Ultimas Noticias newspaper said Friday.
The cause remained under investigation Friday.
Mattresses, blankets and wooden beds quickly caught on fire, Ultimas Noticias said. The burning mattresses also gave off a toxic smoke that filled the prison wing, the newspaper said.
The three prisoners in critical condition suffered severe lung damage from breathing in the toxic smoke and searing gases, Ultimas Noticias said.
Videos of the prison broadcast on Teledoce showed soot-covered concrete walls and burned-out remains of beds and other furnishings.
The father of one of the victims said he blames authorities.
"I think it was negligence by prison officials," Ruben Cardoso said in an interview with CNN affiliate Channel 10.
"When the fire broke out, they delayed too much in opening the door," Cardoso said. "If they had opened the first two locks, all the prisoners would have gotten out."
He last saw his son, Fernando, on Saturday, Cardoso said. He couldn't eat or sleep after visiting his son, the father said.
"He told me about the fears he had about living inside there," he said. "I always thought something bad would happen to my son inside there."
Now, he said, the responsible parties must be held accountable.
"All I want is justice and for this not to happen to any other kid and hurt another family," Cardoso said.