The president also declared three days of national mourning “to honour the memory of a patriot, Fernando Villavicencio Valencia.”

“This is a political crime that acquires a terrorist character and we do not doubt that this murder is an attempt to sabotage the electoral process,” he added.

Lasso has said he will not seek re-election.

President of the National Electoral Council, Diana Atamaint said: “the date of the elections scheduled for August 20 remains unalterable.”

Nine other people were injured in the shooting attack, including a candidate running for the national legislature and two policemen, prosecutors said.

One of the alleged attackers was shot and killed by security personnel. And police detonated an explosive device planted in the area, said chief investigator Alain Luna.

Carlos Figueroa, a friend of Villavicencio’s who was with him at the time of the attack, told local media that the assailants fired around 30 shots.

“They ambushed him outside” the sports centre, Figueroa said. “Some (of those present) even thought they were fireworks.”

The country’s main newspaper, El Universo, reported that Villavicencio was assassinated “hitman-style and with three shots to the head.”

Prosecutors later said six other suspects were arrested in raids carried out in southern Quito and in a neighboring town, and that Villavicencio’s body was brought to a police department and would undergo an autopsy.