A CBS News reporter on stated: "All of a sudden I heard a roar and I saw one of the towers blow ... I saw from street level as though it exploded up , a giant rolling ball of flame..."

A Port Authority Police Department officer, who was intimately familiar with the World Trade Center from his years of police duties patrolling there, said that hallway began to shudder as a "terrible deafening roar" swept over him, then a giant fireball exploded in the street seconds before the south tower collapsed

An eyewitness reported a large explosion at ground level right before the collapse of the North Tower

In addition, a paramedic stated that





See also

(pp. 5-7). What could have caused the ground to shake?See also this and this

On 9/11, there were multiple reports by credible witnesses of ground-level fiery explosions right before the collapse of the Twin Towers: What could have caused ground-level fiery explosions right before the collapse of each tower?