Ask other people.

The mayor may be the best person to ask, but that doesn't mean he's the only one who might know where the others are. Besides, by the time you find a way to get to him, the trail may go cold.

You guess that if they've found their way to the city, they're probably trying to regroup as well. They may show up if you wait near the mayor's office.

You've already seen a few gathering places as well, you may be able to find someone who has seen one of them at an inn, and anyone who hangs around the city's entrances might have spotted them.

Really, there's a whole town of people you could ask. The trouble is how to go about it.