I've long been following Dara Lind's reporting on immigration, at Vox and ProPublica in the past. Here's her excellent recent summary of what's going on DC.
"To understand what’s going on in D.C., it’s important to know that there are two distinct components to the federal takeover.
"One is the deployment of the National Guard – now including six states and counting, in addition to the D.C. guard – that is similar to what we saw in Los Angeles earlier this summer, with National Guard troops being used as a force multiplier to intimidate immigrants and their neighbors and carry out a 'show of force' in areas with high visibility.
"But the second, unique to D.C. and arguably more important, is the Trump administration’s use of the takeover to change rules about how the D.C. police operate."
https://www.americanimmigrationcouncil.org/blog/immigration-enforcement-trump-federal-takeover-dc/
h/t @heidilifeldman