Amnesty International has urged the Mexican authorities to investigate an attack on members of an Indigenous Triqui community in the state of Oaxaca after a man and woman were shot dead by an armed group with alleged links to the authorities.Gunmen ambushed five members of an Indigenous people’s organization near the village of Tres Cruces on Saturday 16 October, killing Teresa Ramirez Sánchez and Serafin Ubaldo Zurita. Two other men and a woman, whose names are withheld to protect them, survived the attack. One remains in hospital.”This attack heightens the need for the authorities to protect the survivors, but also to take immediate steps to restore rule of law and protect human rights in this troubled part of southern Mexico,” said Kerrie Howard, Americas deputy director at Amnesty International. “Armed groups have been operating in the area with impunity for many years. The authorities must act to restore the law, starting with a prompt and thorough investigation into the killings of Teresa Ramirez Sánchez and Serafin Ubaldo Zurita.”The Inter-American Commission on Human Rights this month called on the Mexican authorities to protect the communities.The five victims of the attack, which took place between the towns of Santiago Juxtlahuaca and Yosoyuxi, were members of a political group known as the Independent Movement for Triqui Unity and Struggle (MULTI). The MULTI, supported by 700 Triqui people, established the autonomous Indigenous municipality of San Juan Copala on 1 January 2007.In September 2010, armed members of two other Triqui Indigenous people’s organizations, known as UBISORT and MULT, took over the autonomous municipality of San Juan Copala and occupied the town. All residents identified as belonging to MULTI fled the town and relocated to neighbouring areas such as Yosoyuxi.San Juan Copala was under siege from November 2009 until September 2010, with armed groups surrounding the community and firing into the streets on a daily basis to intimidate local residents, many of whom had supported the MULTI. During the siege food, water and medical supplies were cut off.On 27 April 2010, armed men belonging to UBISORT ambushed a humanitarian convoy near San Juan Copala and killed two human rights defenders. On 7 September, armed men attacked and wounded two indigenous women from San Juan Copala. No one has been brought to justice for these crimes. For many years, armed groups, some believed to have links with local and state authorities, have harassed and killed Triqui Indigenous people because of their perceived affiliation with local Indigenous organizations. The state and federal authorities have taken insufficient action to dismantle the armed groups.