[quote=@Raijinslayer]
Again, I assumed ground level since people said it was like an airport in the back, which woul be a smarter place for holding an evacuation because theirs more space and someplace to run if the enemy gets in.
[/quote]

I think Owlman led some people to the roof because they couldn't get out any other way. Getting a helicopter to the roof was then the only way to get them to safety.