Many people sit, some stand outside of a large brick building.
people are protesting outside of an abortion clinic
You can not infer they are protesting outside an abortion clinic.
People can sit and stand for numerous reasons that are not a protest and not all brick buildings are abortion clinics.  Without knowing this I wouldn't know what that they were protesting or what they were protesting.
Not all building is an abortion clinic and not all people standing outside of a building are protesting.