A question about bees

[Askew]

Got home this afternoon to find about three or four dozen bees in the bathroom. The window was closed, as was the door, and there was no obvious point of entry. Most of the bees were on the floor, lethargic, with some on the windowsill. There were no bees anywhere else in the house that I could find. I collected them up and took them outside, where they became more active. Only one flew away that I noticed.
Anyone have any idea how they got there, and why?
One last thing, these were honey bees not natives.

 

[Hairyman]

Sounds like a bit of a swarm, might have been a queen bee in there somewhere, trying to establish a new hive, usually a lot more
in a swarm though.

 

[Askew]

Thanks Hairyman. I didn't notice a queen, but I didn't check all the bees I collected.

 

[silverback]

Is your floor drain open to the outside? Could be place of entry or they are trying to colonise it.

 

[Askew]

The floor drain is not open to the outside. I did consider the possibility they were trying to start a hive in the wall cavity, but haven't seen any sign of this yet.