Other uses for か besides asking a question

[kanjistream_505991]

I can't wrap my head around this sentence, particularly the underlined part.

しかし、火事になったとき何人泊まっていたかわからないため、逃げるのが遅れた人がほかにもいないかどうか確かめています。

It's not asking a question, that much I can tell. I want to lean on it saying "whether", like in the explaination here -
http://www.learn-japanese-adventure.com/ka-dou-ka.html

- but it only uses "かどうか” as a primary example.

[Murius]

Here wikipedia is your friend :

http://en.wikipedia.org/wiki/Japanese_particles#ka

[community.japanese]

Murius san,
Thank you for helping san.

san,
The sentence is same as 火事になったとき何人泊まっていたかどうかわからないため.
Is it clear?
If you need more explanation, please feel free ask us.

Yuki 由紀
Team JapanesePod101.com