Emergency responders climbed into fuselage to save passengers – Gary Tuchman reports

NTSB investigators continue to try and zero-in today on what caused Asiana Airlines Flight 214 to crash-land at San Francisco's airport, killing two people.

They are focusing on the speed of the plane as it came in for a landing, which was said to be "low and too slow".

But incredibly, more than 300 people survived the crash-landing.

CNN is hearing for the first time from some of the emergency responders who climbed into the fuselage to save some of their lives.

CNN's Gary Tuchman spoke with two fire firefighters who were among the first on the scene.