The video shows the hijacked beer lorry ploughing across a busy street before thundering into a wall.
Screams can be heard as the truck mercilessly runs down pedestrians.
Three people are known to have died and many more are injured.
The Nice-style attack came “out of the blue” according to witnesses who lined Drottninggatan (Queen Street) at the time.
Footage emerges of the truck driving into crowds in Stockholm
But the driver or drivers of the truck are understood to have fled the scene and run into the nearby T-Centralen underground subway station.
Witnesses reported hearing “loud bangs” and possible gunfire before the subway was evacuated.
It remains in lockdown.
Police have released an image of a man they wish to speak to in connection with the attack.
All of Stockholm’s emergency resources are being used to capture those responsible for the terror incident.