This video posted on the internet purports to show part of the disputed events surrounding the shooting of more than 50 people in Egypt's capital on Monday.
The footage on YouTube appears to show a man on a rooftop apparently firing in the direction of the crowd below.
Reuters is unable to independently verify the video.
Two men, bloodied and appearing unconscious, are seen being carried away.
The protesters, supporters of Egypt's ousted president, said the shooting started as they were praying. A least 51 people were killed in Monday's incident outside the Cairo barracks where Mohamed Mursi is thought to be detained.
The military wasn't immediately available for comment on the images. Instead it issued its own video intended to back up its assertion that armed men attacked troops in the area around the barracks. The video appears to show people taking cover on rooftops as they hurl missiles at security forces on the ground.
It also appears to show moments when gunfire was purportedly aimed at the security personnel.
Those moments were slowed down on the video and highlighted with a red circle.
Emergency services said at least 435 people were wounded in Monday's incident, the deadliest since Mursi was toppled by the military.
The bloody scenes from Cairo came after three days of violence between pro- and anti-Mursi protesters across the country.