The heart stopping moment a Good Samaritan saved a man who fell off a train platform was caught on surveillance camera.

Footage from Philadelphia's 15th Street Station shows Alfred McNamee slipping off the platform and falling head first onto the SEPTA tracks on Wednesday evening.

Seconds later, Charles Collins leaped onto the tracks to save McNamee from getting hit by a train. 

The 28-year-old hero pushed the man up and towards the platform edge, where other commuters helped to pull them both to safety. 

McNamee suffered a number of serious injuries, including a broken back. Collins only suffered a minor leg injury.

Watch the incredible video above.