Sound of water flowing through pipes at main but not flowing at taps

I’ve been told by a plumber we have a frozen pipe that runs from our main water supply at the street to our main water valves inside our building. The pipes from the main supply outside to our valves inside are underground, below our main floor, in concrete. I hear strong flowing water in the pipes at the main valves inside. We have two water mains. We only have a trickle of cold water at a few faucets. No hot water flow (meaning no water at all when the hot water faucet is turned on). Toilets won’t flush. There are no frozen pipes inside the building. Any opinion if this is actually a frozen pipe leading from the main water supply outside to our main valves inside or if it’s a different issue? We had the main water supply checked by the water company at the street where our line make way into our building and it’s fine. I’m wondering why I can hear water flowing through the pipes at the main valves inside but we don’t have water. Thank you for any advice! We’ve been closed for 8 days and we’ve been told to "wait it out" until the temperature increases above freezing which it has for the past 2 days.