This might have been near a hospital. That’s where they were holding some of the news conference.
One of the responses to that Twitter post surmising that the building was a mosque was “That’s the Christ Church of Orlando, dummkopf.”
And, through the magic of Google Streetview, we have confirmation. The building some Twitter fool guessed was a mosque, is, indeed, the Christ Church of Orlando. See here:
https://goo.gl/maps/WMfKkDk3AMM2