Kitchen Gas Appliances - Can't find gas dryer shut off valve

There is a gas smell coming from our dryer and we can't find the shut off valve. The connector between the main gas pipe and the flexible gas pipe going to the dryer contains a bolt which we were able to turn to the right - is this the shut off? All others I've seen have more of a nob or valve - this is just a bolt. We can't find something that looks more like a valve anywhere. The house is older (1950s) and we just bought it, so we're not sure where things are...

The dryer itself tumbles but won't heat. We were going to look at the heating element, but smelled the gas so wanted to turn off the gas before doing anything...

Should we call the gas company for help?

Thanks.

Is the "bolt" on a brass body? Some of the older gas valves had square heads that only turn 90° from on to off. Some have a line scribed into them and it signifies whether the gas is going through the valve or (when crossways) the gas is off. Good luck.