Does a provincial government, assuming this is the act of the provincial government and not just the governor, have the authority to restrict the entry and exit of persons to and from the province? 
It seems to me that that power is not lodged in the local governments, but in the national government. It seems to me that there must be a law duly enacted by Congress to authorize the President to restrict the flow of persons, and a joint resolution from an interagency task force, even if duly approved by the President, will not be enough.
Our laws are not suspended even during times of a national health crisis.