As an example, during the infancy of the armed struggle under apartheid, the ANC's armed wing conducted a campaign of bombings that targeted things like power substations, power lines, empty government posts etc.
I absolutely see that as justified.
Murder of civilians is not justified under those circumstances as a few members committed in later years.
As to the Police Station having police in it... well... context is always important.
I'm never one to condone violence, but let's say in America no, the police station would be empty.
Let's repaint a picture.
Saddam Hussein is still in power, protesters overrun a police station and find officers inside known to have tortured men and raped women in the locale... what do you think is gonna happen there and how would it make you feel?