Right to Privacy vs Sheriff Garber's cameras

On Pas pa tout this morning Sheriff Garber's new Lafayette camera center was featured.  Garber was very proud of this new center which has a staff of 10 law officers monitoring live cameras around Lafayette to keep an eye on things.  Garber bragged how they saw a man pull a gun out of his coat pocket and then put it back in.  IE they are not searching for people who have committed a crime (which I thought took a warrant) but they are watching the general population in case they see anyone committing a crime.  I know that it is legal for business places to have cameras to protect their property, but from what little I know of the law, the camera film must be suppoened by a warrant even if a crime has been committed.  What Garber and our Lafayette government have going on here is the same thing going on in Red China where the state uses facial recognition etc to track their opposition.  Isn't this illegal?