It is clear that when the soldiers find the woman they have called a "spy" that they are very violent and threatening. Remember this is narrated using the third person limited point of view - everything is seen from Omovo's vision, which heightens the shock of seeing a woman treated in this fashion with the threat of impending violence. The soldiers call the woman a witch and one of them begins to slap her to try and make her tell where the "others" are. Then a soldier rips the woman's veil from her:
Her head was bald, and disfigured with a deep corrugation. There was a livid gash along the side of her face. The bare-chested soldier pushed her. She fell on her face and lay still.
It is interesting that at this point Omovo recognises that what he thought were dead animals on the river banks were actually dead men - seeing this violence has opened his eyes to other acts of violence that he had previously been blind to. The woman then gets up, and spits at the soldier in the face. The soldier then shoots the woman in cold blood and Omovo flees.
The shock of these events is heightened by the use of the narrative style - these events are shared with us just as they are with Omovo - we are silent observers of these atrocities and therefore share the same shock and feelings of guilt and horror that Omovo feels.