Sixty-eight people have died in a prison riot in northern Venezuela, Attorney General Tarek William Saab said late Wednesday.

Initial reports had said that five people had died when inmates at a detention center at the regional police headquarters in Carabobo state took a guard hostage and set fire to mattresses.

However, Saab said in a series of tweets that the dead comprised 66 men and two women, who were visiting the prison overnight.

An investigation would be launched immediately to clarify what had happened, he added, saying that four prosecutors had already been assigned to the case.

He said that four prosecutors have been named to determine what happened in Valencia, a town about 100 miles from Caracas.

Local officials had earlier confirmed only that there had been fatalities. They said they were working to determine the exact number and declined to provide any estimates "out of respect for the families."

Distraught relatives clamoring for information about detained loved ones clashed with police outside the station during the day. Officers used tear gas to disperse the crowd.