The influx came the morning after the Republican president announced he would be activating the guard members and taking over the District’s police department, something the law allows him to do temporarily.

The president said he was declaring a public safety emergency and his administration would be removing homeless encampments.

D.C.’s mayor acknowledged local officials could do little to block what was expected to be a 30-day takeover of the capital’s policing. President Trump suggested his action might be expanded to other cities.