Why is 'unharmed' put after the verb in this sentence [closed]

This comment from BillJ appears to be an answer, so here it is as an answer:

The adjective unharmed is here called a predicative adjunct: "predicative" because it refers to a predicand — people — and an "adjunct" because it's a modifier in clause structure, i.e. it's located in the verb phrase ("managed to get out of the building in the explosion unharmed") not in the subject noun phrase, which is just "people".