Two gunmen are believed to have carried out the attack, with police investigating whether others were involved. One of the gunmen was killed, with a second in “critical condition,” police say.
The footage of Mr Ahmed’s intervention has been shared widely online.
It shows one of the gunmen standing behind a palm tree near a small pedestrian bridge, aiming and shooting his gun towards a target out of shot.
Mr Ahmed, who was hiding behind a parked car, is seen leaping out at the attacker, who he tackles.
He manages to wrestle the gun from the attacker, pushes him to the ground and points the gun towards him. The attacker retreats.
He then lowers the weapon and raises one hand in the air, appearing to show police he was not one of the shooters.
Nearby on the bridge, another gunman continues firing. It’s unclear who or what he is aiming at.