The U.S. Border Patrol says agents served a search warrant at a southern Arizona humanitarian aid camp and arrested four Mexican citizens suspected of being in the country illegally.
The federal agency said agents on Wednesday tracked the men walking north on a known smuggling route before the four entered the camp run by No More Deaths/No Mas Muertes, an organization that provides care for migrants along the U.S.-Mexico border.
The Border Patrol said talks between agents and camp representatives on gaining access to question the men about their citizenship and legal status were unsuccessful. Agents then obtained a search warrant, the agency said.
The aid group released a statement Thursday saying a helicopter, 15 trucks and 30 armed agents were used in arresting four people receiving medical care as desert temperatures exceeded 100 degrees.
The camp is located near Arivaca, Arizona, which is 51 miles (82.1 kilometers) southwest of Tucson.
Camp officials said surveillance began late Tuesday and that the law enforcement presence "has deterred people from accessing critical humanitarian assistance during this hot and deadly weather."
"Obstruction of humanitarian aid is an egregious abuse by the law enforcement agency, a clear violation of international humanitarian law and a violation of the organization's written agreement with the Tucson Sector Border Patrol," the group's statement said.
The Border Patrol said a similar incident occurred a month ago and that negotiations resulted in the surrender of eight people who were taken into custody. Those included two individuals with "prior significant criminal records in the United States" and two needing medical care at a hospital, the agency said.
The agency said it "wants to stress the dangers of illegally crossing the border. If anyone needs help, the Border Patrol advises them to call 911 immediately as delays could result in loss of life."