Really hard to tell how large because it was spread out along the length of the street.
Most accurate crowd estimate I’ve heard so far is “goodness that was a lot of people.”
Here in Saint Paul, there were people protesting ICE spread out across many intersections - even if individual groups have been small.
If you have a fediverse account, you can quote this note from your own instance. Search https://mastodon.online/users/michael_w_busch/statuses/115873747780324392 on your instance and quote it. (Note that quoting is not supported in Mastodon.)