You will need to contact the city to have the municipal water shut off while the repair is made. A leak like this can quickly get worse and before you know it, your entire house can be flooded with no way to shut off the water.
If the leak gets worse and you can't get a hold of the city, you can call the city police on their non-emergency number and they can usually get someone down to shut the water off for you.
You appear to have a 3/4" supply pipe that is reduced down to 1/2" before the shutoff. You also have a threaded connection on the main line which is another potential point of failure.
I'm not a fan with how they originally installed it. It would be better to have a ball valve installed right to the stub coming out the floor instead of how it is now. Then you could reduce it down to 1/2", hook up the meter, etc.