Six men were murdered in a Guayaquil prison complex Friday, prompting Ecuador President Guillermo Lasso to call an emergency security meeting and to cancel an official visit to South Korea.

Local newspaper El Universo reported that the men may have been suspects in the assassination of presidential candidate Fernando Villavicencio. The prison service said the victims were being identified, while the Interior Ministry didn’t reply to requests for comment. More than 400 people have died in riots in Ecuador’s prisons since 2020.

Villavicencio’s killing highlighted the growing power of organized crime that has made the nation one of the world’s most violent. The trigger man who shot the candidate was injured by a policeman and bled to death the night of the murder while in custody.

Villavicencio, an anti-corruption campaigner, was gunned down two weeks ahead of the first round of nation’s presidential election after he pledged to get tough on cocaine-smuggling mafias.

Read more: What a Candidate’s Assassination Means for Ecuador: QuickTake

The runoff vote between businessman Daniel Noboa and socialist candidate Luisa Gonzalez is taking place on Oct. 15. The campaign has been dominated by debate over how to deal with the soaring drug violence that has led Ecuador’s homicide rate to overtake those of Colombia and Mexico.