The president of Oglala Sioux Tribe in South Dakota on Tuesday called for the immediate release of tribal members who were detained at a homeless encampment by Immigration and Customs Enforcement agents in Minnesota last week.

Three of the four Oglala Sioux Tribe members who were arrested in Minneapolis on Friday have been transferred to an ICE facility at Fort Snelling, President Frank Star Comes Out said in a statement released with a memorandum sent to federal immigration authorities.

“The Oglala Sioux Tribe’s memorandum makes clear that ‘tribal citizens are not aliens’ and are ‘categorically outside immigration jurisdiction,’” Star Comes Out said. “Enrolled tribal members are citizens of the United States by statute and citizens of the Oglala Sioux Nation by treaty.”