While the video doesn't show from where the gunfire originates, just moments after the sounds of an automatic weapon are heard, a bloodied man is rushed past the cameraman to safety. As the camera pans up, a crouching figure is clearly visible on a nearby roof, firing what looks like a rifle into the crowd.
A moment later, a second wounded man, who appears to have sustained serious injuries, is rushed to a nearby pickup truck.
The video was purportedly filmed outside the Cairo headquarters of the Egyptian army's elite Republican Guard, The Washington Post notes.
While we cannot confirm the clip independently, witnesses said the Egyptian army on Monday fired on a group of pro-Morsi protesters who were demonstrating near the army headquarters, CNN reported. According to Egypt's Health Ministry, at least 51 people were killed in the clashes, and hundreds were wounded.
The army says it was only defending itself against gunmen who killed an army officer and two police officers, the Associated Press reported.
Egypt's Freedom and Justice Party, the political arm of the Muslim Brotherhood, described the incident as a "massacre" on Monday and urged its supporters to rise up against the army.