Dozens of federal agents raiding an entire apartment building with kids in it just to see what they can find. It’s the most egregious abuse of our basic rights as Americans I've seen in a long time, maybe in my lifetime,”
		
		
	 
If what he's saying is 100% true, then he's right, it is illegal. 
There is no such thing as a warrantless search unless they have
probable cause to make an arrest. 
This apparently goes beyond even that. Even with probable cause
that illegal immigrant gang members might be present in an
apartment building, you can't just drag innocent civilians, including
children out of their apartments with the excuse that you are looking
for someone or something, and lock the kids in vans. 
These agents can be charged with kidnapping, false imprisonment,
endangering the welfare of minors, and unlawful search and seizure.