Foreign nationals belonging to organized crime groups are the suspects in the assassination of Ecuadorian presidential candidate Fernando Villavicencio, the government said on Thursday, adding that it is pursuing the "intellectual authors" of the murder.

The fatal shooting on Wednesday night, less than two weeks before the election, has sent shockwaves through the South American country, leading some rivals to suspend campaigning and bringing the issue of rising violence to the foreground.

Villavicencio, a vocal critic of corruption and organized crime, was killed leaving an evening campaign event at an education facility in northern Quito.

A suspect in the crime later died of injuries sustained in a shoot-out and six others have so far been arrested, the attorney general's office said. Nine people, including a candidate for the legislature and two police officers, were injured, it added.

The dead suspect was arrested on weapons charges in July, the government said on Thursday, adding that the six who were detained were all foreign nationals who belong to organized crime groups, without providing other details. The nationality of the dead suspect was unclear.

"The national police now have the first arrests of the alleged material authors of this abominable event and will employ all of their operative and investigative capacity to discover the motive of this crime and its intellectual authors," Interior Minister Juan Zapata told journalists.

President Guillermo Lasso said the crime was clearly an attempt to sabotage the election, but that voting would go ahead as planned on Aug. 20, albeit amid a national state of emergency, with the military mobilized to guarantee security.

Lasso also declared three days of mourning.

Violence in Ecuador has surged in recent years, especially in cities along drug-trafficking routes like Guayaquil and Esmeraldas where citizens say they live in fear.

Several Latin American countries have seen similar issues since the coronavirus pandemic.

Villavicencio's party Movimiento Construye on Thursday rejected what it said was "political use" of his death and called for a speedy investigation in a statement posted on X, the social media site previously known as Twitter.

The party condemned an unverified video circulating on social media purportedly from a gang called Los Lobos, or The Wolves, claiming responsibility for Villavicencio's killing, alleging he had received millions of dollars from them for his campaign and threatening fellow candidate Jan Topic.

Neither the police nor the attorney general's office responded to requests for comment about the authenticity or origin of the video, which features more than a dozen black-clad and masked men waving high-powered rifles.

Movimiento Construye said: "Those who sit to negotiate with mafiosos, those who give them microphones, those who generate fear campaigns with trick videos in the name of criminal organizations and who take the name of Fernando Villavicencio in vain with lies are responsible for the crime."

Los Lobos have thousands of members, according to some reports, and are active in the country's violent prison system.

Former President Rafael Correa, who was heavily criticized in office by Villavicencio, then a journalist, reposted the video overnight, but said in a post on Thursday morning that it was fake, without providing more information.

Villavicencio had been sentenced to 18 months in prison for defamation over statements made against the former president, but he fled to Indigenous territory within Ecuador and later was given asylum in Peru, before returning after Correa left office.

"Ecuador has become a failed state," Correa, who now lives in Belgium, said on X on Wednesday. "Hopefully those who try to sow more hate with this new tragedy will understand that will only continue to destroy us."

Candidate Luisa Gonzalez, who is running for Correa's party and leading with 29.3% support, expressed horror at the killing, but did not suspend her campaign.

Indigenous candidate Yaku Perez and law-and-order hopeful Topic both suspended their campaigns, while businessman Otto Sonnenholzner begged the government to take action.

Perez said on Thursday he had spoken with Sonnenholzner and three minor candidates and left messages for Gonzalez and Topic. He hoped to hold a meeting with the candidates and the Catholic Church to discuss a "national security agreement," Perez said, without providing further details.

Villavicencio's party said on Wednesday that discussions had been held about whether to suspend campaigning due to recent political violence, including the July murder of the mayor of Manta.

Villavicencio opposed a suspension, it said, saying it would be an act of cowardice.

The party can choose another candidate, the electoral court said, but ballots have already been printed and distributed and Villavicencio's name and photo appear on them.

Villavicencio, who police said had three rings of security on Wednesday, had on Tuesday made a report to the attorney general's office about an oil business, but no further details of his report were made public.

There were 3,500 violent deaths in Ecuador in the first half of the year, according to police figures, with nearly half occurring in the largest city, Guayaquil.

Lasso, who called the elections early amid an impeachment bid against him, has been criticized for failing to tamp down violence, despite using emergency powers to authorize soldiers to patrol the streets and use their weapons against criminals.

His government blames bloodshed on the streets and in prisons on criminal infighting to control drug trafficking routes used by Mexican cartels, the Albanian mafia and others.

Beyond security, employment and migration are major issues in the presidential contest.

Villavicencio, a married father, had 7.5% support in polls, placing him fifth out of eight candidates.

His body will be released to two people chosen by his wife, including his lawyer, the attorney general's office said on X.

Countries lined up to condemn his assassination and call for a full investigation.