Watch | US commuter thrown on tracks in horrifying metro robbery

Dramatic video of an attack on a commuter, who was robbed, shot with a stun gun and pushed onto the tracks near the live rail has been released by US transit police.

Southeastern Pennsylvania Transportation Authority officials say the man was dozing in a car. That's when the attackers, a man and woman, pounced grabbing his backpack and running off the train as it pulled into the platform.

Surveillance video shows the victim jolting awake and chasing after them. He succeeds in wrestling the male attacker to the floor before his female accomplice shoots him the stun gun causing him to fall backwards onto the tracks.

The video shows him slowly getting to his feet, then tripping and landing on the electrified third rail. A transit official says a thin cover on the rail prevented him from being electrocuted. The robbers are then seen running off with the backpack.