A mayoral candidate in Mexico was assassinated Monday at a campaign event in the city of Celaya in the state of Guanajuato. Bertha Gisela Gaytán was shot dead shortly after she outlined her plans to increase security in the city.

Bertha Gisela Gaytán: “The citizens are with us and look after us. Of course, we will have security protocols, which the legal department of the party in the state is reviewing.”

Gisela Gaytán was a member of the ruling Morena party. The Associated Press reports at least 15 political candidates have been killed in Mexico since January ahead of nationwide elections on June 2.