Ecuadorian presidential candidate Fernando Villavicencio was assassinated at a campaign rally on Wednesday evening.
In the wake of the shooting, Ecuadoran President Guillermo Lasso declared a nationwide state of emergency for 60 days.
How did the killing take place?
Footage of the incident shows Villavicencio leaving the event and entering a vehicle when gunshots can suddenly be heard.
He was wounded and taken to a nearby medical center before he died. It was initially unclear how many other people at the event were injured during the shooting.
"The Ecuadorian people are crying and Ecuador is mortally wounded," Villavicencio's campaign adviser Patricio Zuquilanda told the Associated Press.
"Politics cannot lead to the death of any member of society."
The suspect died from injuries sustained during a shootout with police, according to the Attorney General's office.
The office later said it had detained six people so far in connection with the crime during raids in Quito.
Villavicencio was one of eight candidates in the election scheduled for August 20. The vote is still set to take place, the head of the National Electoral Council said Thursday.
Opinion polls consistently put him in fifth place in recent weeks.
President vows to tackle organized crime
Ecuador's President Guillermo Lasso confirmed the killing on social media and vowed to hold the culprits accountable.
"For his memory and his fight, I assure you that this crime will not remain unpunished," Lasso said.
"Organized crime has gone very far, but all the weight of the law will fall on them."
He said he would host an urgent meeting with top security officials.
Ecuador's former Vice President Otto Sonnenholzner — a candidate himself — said, "we demand that you do something" at a press conference after the shooting.
"We are dying, drowning in a sea of tears, and we do not deserve to live like this," he said.
Who was Fernando Villavicencio?
Villavicencio, 59, was a former union member at state oil company Petroecuador and later worked as a journalist who denounced alleged millions in oil contract losses.
He was elected to Ecuador's National Assembly in 2017 and remained in parliament until May 2023.
Villavicencio was one of eight candidates in the upcoming election and was supported by the Build Ecuador Movement.
He was one of the most critical voices against corruption, especially during the government of former President Rafael Correa from 2007 to 2017.
Zuquilanda said Villavicencio had received death threats in recent weeks, and he traveled with police protection amid the country's gang violence epidemic.
Villavicencio was married and is survived by five children.
How did Ecuador and the world react?
Luisa Gonzalez, the frontrunner in the polls, expressed her condolences.
"This makes us all mourn, my solidarity to all his family," she said. "This vile act will not go unpunished!"
Another candidate, Daniel Noboa, said the assassination was "an attack against the country, democracy and peace of all Ecuadorians."
The shooting was also condemned from overseas.
"We urge all candidates to strengthen their security measures and call upon the authorities to provide the necessary support to guarantee the integrity of the participants in the electoral process," the Organization of American States said in a statement.
"The security of candidates is fundamental to maintaining confidence in the democratic system."
The US ambassador to Ecuador, Mike Fitzpatrick, said he was "deeply dismayed" by the assassination.
He called Villavicencio a "fighter against the corruption and narco-criminals who have done so much damage to Ecuador."