Sergeant Munley, who no longer works at Fort Hood and lives in North Carolina, testified for 21 minutes in a matter-of-fact tone about the events that irrevocably changed her life. She looked at him throughout her testimony, and he often looked at her.

The jury saw video from her dashboard camera as she sped to the scene and parked, the sound of gunfire registering as loudly as someone pounding on a door. She and Sergeant Todd, who arrived separately, then encountered Major Hasan, who had emerged from the building where the shootings had taken place. “We began taking fire,” she said. “I saw a red flash, a laser, come across my eyes.”

Major Hasan ducked around a corner of the building, she said, and rather than follow him, she recalled her training and ran down the side of the building the other way. As he came into view, she fired from a prone position, but “he was running toward my direction,” she said, so she stood up and took cover behind the corner of the building. He then came around, and the two began “blindly” exchanging gunfire. Struck, she fell.

Major Hasan rushed toward Sergeant Munley, and she said she tried to fire, but her 9-millimeter gun malfunctioned. “I see him standing over me trying to fire his weapon as well,” she recalled. He had kicked her gun out of the way, and she tried to drag herself to it. As Major Hasan stood, having trouble with his weapon — he told a military panel in 2010 that he could not use his hand because she had shot him twice — Sergeant Munley said she heard Sergeant Todd shout at Major Hasan to drop his weapon and then heard the gunfire that ended the confrontation.

Her testimony came at the end of the second week of Major Hasan’s military trial. A jury of 13 senior Army officers has heard testimony from more than 70 witnesses called by the prosecution. Inside a courthouse that has been placed under tight security, Major Hasan has been a calm and meek presence, sitting quietly as dozens of people he shot walk by him to the witness stand.