MEXICO CITY — A ruling party mayoral candidate was shot dead on Monday in central Mexico during an event on the first day of her campaign, despite having requested security protection from authorities and receiving no response.

A city council candidate was also initially reported as fatally shot in the incident, but the security ministry later said the person was missing.

On Monday evening, Gisela Gaytán had just presented her security strategy plan before a rally in Celaya, Guanajuato, when gunmen opened fire, killing her instantly.

Guanajuato’s state prosecutor said it was investigating the killing. No arrests have been made.

The reasons why Gaytán was targeted were unclear but Guanajuato state has in recent years registered some of the highest numbers of homicides in Mexico and experienced turf wars between criminal groups.

Security analysts say most electoral violence tends to occur at municipal level, where gangs exert pressure to influence the outcome in the hope of securing more control over drug trafficking and other criminal rackets.

“It is increasingly clear who exercises real power in the territories where there is crime, it does not matter which party is in power,” said Vicente Sánchez, an expert in security and politics at the College of the Northern Border, a think tank. “It is still organized crime groups that decide who the candidates are.”

Mexican elections have been marred by political violence for years, but figures suggest it is getting worse. Several dozen politicians and candidates were killed in the lead-up to the mid-term elections in 2021. According to Mexico City-based research organization Civic Data, there was a 236% increase in political electoral violence in the country between 2018 and 2023.

A report by political risk consultancy Integralia found 24 aspiring electoral candidates were killed between Sept. 1 and April 1, while the government on Tuesday said 14 people who had publicly stated they would run in elections had been assassinated since October 2023.

Gaytán, a 38-year-old former litigator, was the only female candidate in Celaya, one of the deadliest cities in the world and one of the most dangerous places to be a police officer in North America.

In a six-second video shared widely on social media, supporters at her rally are seen carrying party flags and shouting “Morena, Morena,” for President Andrés Manuel López Obrador’s ruling National Regeneration Movement (MORENA) party. Seconds later, six gunshots sound and the crowd quickly disperses.

Reuters could not determine the original source of the video.

Morena candidate for city council Adrián Guerrero was reported missing by the security ministry after the attack. Another two people were injured.

Earlier in the day, Gaytán told reporters that Morena had requested security from the state for her campaign. “We are looking at the issue to see how it can be resolved,” she said. “Let’s see if they have an answer for us today.”

Security Minister Rosa Icela Rodríguez promised justice at a press conference on Tuesday and said the investigation would include an inquiry into why Gaytán had not received protection from state or municipal authorities.

She acknowledged Morena had requested security measures for all its candidates in early March from the country’s National Electoral Institute, INE. Guanajuato’s state electoral body, she said, responded it had yet to start the process needed for the security protocols.