Ecuadorian presidential candidate Fernando Villavicencio has been shot and killed by an unidentified gunman while at a political rally in the country’s capital of Quito, president Guillermo Lasso said.

The killing on Wednesday comes amid a startling wave of violence in the South American nation, with drug trafficking and violent killings on the rise.

Mr Lasso suggested organised crime was behind his slaying. Villavicencio was one of eight candidates in the August 20 presidential vote, though not the frontrunner.

“I assure you that this crime will not go unpunished,” Mr Lasso said in a statement.

“Organized crime has gone too far, but they will feel the full weight of the law.”

Ecuador’s attorney general’s office said a suspect in the assassination of Villavicencio died of wounds after being arrested by authorities.

Videos on social media appear to show the candidate walking out of the event surrounded by guards.

The video then shows Villavicencio entering a white truck followed by gunfire, information that was confirmed to the Associated Press by Patricio Zuquilanda, Villavicencio’s campaign adviser.

Mr Zuquilanda said the candidate had received death threats before the shooting, which he had reported to authorities and resulted in one detention.

He called on international authorities to take action against the violence, attributing it to rising violence and drug trafficking.

“The Ecuadorian people are crying and Ecuador is mortally wounded,” he said.

“Politics cannot lead to the death of any member of society.”

Police confirmed that several others were injured, including officers, describing the incident as a terrorist act and promising to get to the bottom of the killing.

The politician, 59, was the candidate for 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. He filed many judicial complaints against high ranking members of the Correa government.

He was married and is survived by five children.