SÃO PAULO, BRAZIL — On April 30, a group of ranchers armed with rifles and machetes attacked a settlement of about 400 families from the Gamela tribe, in the state of Maranhão, in northeastern Brazil. According to the Indigenous Missionary Council, an advocacy group, 22 Indians were wounded, including three children. Many were shot in the back or had their wrists chopped.

Soon after the attack, the Ministry of Justice announced on its website that it would investigate “the incident between small farmers and alleged indigenous people.” (Minutes later, the word “alleged” was removed.)

This shouldn’t have come as a surprise. It was the third reported attack on Gamela people in three years and part of a trend of assaults against indigenous Brazilians. Every week seems to bring reports of a new atrocity committed against indigenous people in some remote part of the country. But nothing seems to shock our society anymore. Not even when, a few weeks ago, a 1-year-old from the Manchineri tribe was shot in the head.

These attacks are part of a larger pattern of abuse, marginalization and neglect. Since 2007, 833 Indians have been murdered and 351 have committed suicide, according to the Special Secretariat for Indigenous Health — rates far above the national average. Among children, the mortality rate is two times higher than in the rest of the Brazilian population.