Yes, the story lacks critical details. Were I to venture a guess, I’d speculate that the teachers heard gunshots and immediately demanded that Government keep them all safe. Since this is speculation I reserve the right to edit or amend my comments at a later time.
If they were there collecting water samples with a teacher, that tells me all I need to know about the intelligence of the teacher. Stay in harms way to prove a point and create a ruckus against those evil gunmen.