(CNN) The Evangelical Lutheran Church in America, which represents nearly 3.5 million Christians, voted Wednesday to become the country's first "sanctuary church body," according to church officials .

The measure, approved during a churchwide assembly in Milwaukee, pledges that in addition to providing shelter for undocumented immigrants , the ELCA could:

-- Respond to raids, deportations and the "criminalization" of immigrants and refugees;

-- Fight individual cases of deportation, press for the end of mass detentions and lift up immigrants' voices;

-- Take "prophetic action" to extend "radical hospitality" to immigrants and immigrant communities.

The measure, called a "memorial," notes that some ELCA churches and organizations, such as its Metro New York Synod, are already carrying out these actions. A church committee plans to study what it means to be a "sanctuary church body" and issue a report in 2022.

The ELCA will also develop guidelines and resources for the denomination's more than 9,000 congregations "to help them explore and develop sanctuary ministries," according to church officials.

Despite their name, the Evangelical Lutheran Church in America is distinct from the larger evangelical Christian movement, which tends to be more politically and theologically conservative.

"Christians have offered sanctuary for 2,000 years, continuing an ancient biblical practice in which cities and houses of worship provided refuge and asylum for people fleeing injustice," said Christopher Vergara, who works on immigration issues in the ELCA's Metro New York Synod.

Vergara also tied Wednesday's measure to the "Sanctuary Movement," which began with churches in the 1980s assisting refugees from Central America.

"Today, the New Sanctuary Movement is a revived effort to protect undocumented migrants from needless jailing procedures and deportation, and to address the dire situation within the Department of Health and Human Services that has resulted in the stripping of services to refugees and unaccompanied children."

None of the proposed actions break US law, the church said. More than 800 churches and other faith communities have stepped up to provide sanctuary to undocumented immigrants in recent years, according to the National Sanctuary Movement.

Officials with a warrant can arrest undocumented immigrants regardless of whether they're at a church, synagogue or mosque, though US Immigration and Customs Enforcement, or ICE, has said it generally avoids arrests at "sensitive locations," including houses of worship.

The ELCA's presiding bishop, the Rev. Elizabeth Eaton, and more than 700 others marched earlier Wednesday to ICE's Milwaukee office, where they held a prayer vigil, church officials said and CNN affiliates reported

The march and sanctuary measure came in response to the Trump administration's immigration policies, including the detention of migrant children and families entering the United States at the southern border.

"It just keeps getting worse and worse in terms of unaccompanied children, separated families, detention centers that are just horrific, and so what we wanted to say as a church body, as the Lutheran church, we wanted to now act with our feet and take action," Evelyn Soto Straw, an official with the ELCA's domestic mission programs, told Religion News Service.

US immigration authorities on Wednesday detained some 680 undocumented immigrants in what a federal prosecutor described as a record-setting operation

Arrests took place at seven sites in six cities in Mississippi, US Attorney for the Southern District of Mississippi Mike Hurst told reporters. The raids, he said, are "believed to be the largest single-state immigration enforcement operation in our nation's history."

"These are not new laws, nor is the enforcement of them new," ICE Acting Director Matt Albence said Wednesday. "The arrests today were the result of a year-long criminal investigation. And the arrests and warrants that were executed today are just another step in that investigation."