Fernando Villavicencio speaks during a campaign event at a school minutes before he was shot to death in Quito, Ecuador, on Wednesday night. AP

"They fired 30, 40 shots with submachine guns. We saw the wounded fall. I know there were some deaths, and tragically the murder of Fernando," Villavicencio's uncle, Galo Valencia, told reporters. "We lived through a horror movie."

Villavicencio, a journalist and anti-corruption crusader, had already been campaigning under police protection ahead of Aug.20 elections, and had complained of receiving threats from the Los Choneros organised crime gang.

The suspects in the assassination of Villavicencio are foreign nationals who belong to organised crime groups, the government said on Thursday, adding that it is pursuing the "intellectual authors" of the murder, Reuters reported.

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. 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 organised crime groups, without providing other details. The nationality of the dead suspect was unclear.

DAY OF MOURNING DECLARED

Ecuador, once a peaceful nation wedged between major cocaine producers Colombia and Peru, has in recent years seen an explosion in violence between drug gangs.

Villavicencio, 59, had exited the building where he had held a political rally and had just got into his car when the gunfire started. "There were a lot of shots," said a friend of the candidate, Carlos Figueroa. "Some people even thought they were fireworks."

Villavicencio was taking his first run at the presidency, and Figueroa said he tried to hold events in closed locations "precisely because of the danger he faced."

CALLS FOR JUSTICE

Streaks of blood could be seen along the tiled floor of the sports complex where the rally was held. At least nine people were wounded in the attack, including a parliamentary candidate and a police officer, while one assailant was killed in the crossfire.

The candidate's uncle Valencia, slammed the security provided to his nephew. "We don't understand where the police were, where the police guard was," he said angrily. He added that there could have been even more victims, noting that police had to carry out a controlled detonation of an explosive device found nearby.

Villavicencio's body was taken to hospital, where anguished supporters shouted, "Fernando the brave! Fernando, you will live forever!"

Meanwhile, the outpouring of grief over the killing extended to the province of Chimborazo, where Villavicencio was from.

There, his supporters called out for "justice," while carrying posters featuring his face and the caption "Fernando Villavicencio president."

The day after the attack, bouquets of white roses lay at the scene, along with a banner reading "the narco-politicians will pay."

Villavicencio's journalistic investigations exposed a vast graft network which led to former president Rafael Correa being sentenced to eight years in prison.

According to the latest figures, Villavicencio was polling second in the presidential race, behind Correa ally Luisa Gonzalez.

Last week, Villavicencio twice denounced threats against his life and his campaign team.

"Despite the new threats, we will continue fighting for the brave people of our #Ecuador," he wrote on Twitter, now called X. Six people have been arrested in connection with the attack.