According to dictionaries, especially in American English, people say "we have a situation here" when they have "an important or sudden problem".
I am not a native speaker so I can speak for what I know. That is I often hear American people say "we/I have a situation here" for problems relating to bathroom.
For example, a man went into a public toilet and after he was done he realized that there is no toilet paper in there. So, he cried "I have a bit of a situation here".
Or a man is currently on a bus and suddenly he wants to use the bathroom but there is no bathroom on the bus. So he cried "I have a situation here".
Do we say "we have a situation here!" for big serious problems in American English?
For example, many soldiers were killed in the ambush and only one soldier survived and made it to the military base.
Can he say to the general there "We have a situation here!"?
Also, what do British people say in these situations?