shooting scene and the man was back. dressed all in black. i want to say a black helmet, definitely a black gas mask. he had also it looked like i thought it was a toy rifle strapped around. reporter: it must be a stunt of some sort, thought dave. he threw a canister into the audience. i thought, okay, cool. then it went off. i realized it wasn t a firework, it was an actual canister of some toxic gases. reporter: that s when it dawned on him, that was a gas mask. and from the tear gas he realized this was no stunt. as soon as the gas canister went off, people were screaming, shots were being fired. it sounded like a continuous pop, pop, pop, pop. only silence from the gunman who said nothing. it didnprocessed to me to st running and get out of there.