Rare news footage of the second plane hitting the World Trade Center on 11 September, 2001, has been unearthed online.

We didn't know it was the second plane hitting the other tower ... it will never know how many people fell or jumped from the Twin Towers. Estimates put it as at least 37 and probably more ...

Seconds later, the audio captures the pilot asking the tower: “Southwest 2504, how’d that happen?” The second plane, described as a business jet, entered the runway without authorization ...

Seconds later, the audio captures the pilot asking the tower: “Southwest 2504, how’d that happen?” The second plane, described as a business jet, entered the runway without authorization ...