All modern pistols have anti-drop safeties, so that would have had to fail, too.
"He landed and as he picked up his gun from the floor, it fired."
And there you have it, *HE* fired it, accidentally, by having his finger in the trigger guard area when he picked it up. Almost even visible in the video. It didn't go off from being dropped.
"Denver police spokesman Marika Putnam said she does not know what type of gun the agent was carrying."
So we also don't know what it was- old, new, service or what.