They didn't just "stand there and watch". They ran to ensure their own safety. Big difference.
Even if there's is slightest chance to save that girl you won't even try save her?
I would much rather try to save myself, given that she'd probably die anyway. No point in us both getting killed.
Just Imagine if something similar happened to one of your dearer or nearer ones. Would've you have just stood there?
Depends on how near and/or how dear they are. If they were my parent/sibling, sure I'd try to save them.
You could make the same stupid argument about homelessness. Why do you not take random homeless people into your house and care for them and their wards? You would probably do that for someone near & dear to you. Does that make you a greedy little shit? No. Why? Because people have priorities and that is OK.