My best guess is that you managed to hurt the chubby citizen somehow during combat (could be splash damage from a grenade, pyrokinesis, etc.), which made all of them turn against you. He is missing some health, and they've all got red labels above their heads, which clearly means they're hostile to you. Unarmed civilians tend to run around when fighting begins, so they can be a liability if you want to keep them safe.
Regardless, even if you remain hostile with them, there will be no long-term consequences, so it's up to you whether you replay the encounter or roll with it. Even if they all die or remain in captivity you still have the means to progress the story.
