alex, that he had in his car? what more did we learn about that? >> reporter: we know that he had a lot of it. he had 50 pounds of an explosive called tannerite. that's a binary explosive which means it needs two ingredients. they have to combine to create 50 pounds, which is really quite easy to set off. you can fire a single round into the tannerite and it blows up. he had some of hundred rounds of ammunition alongside that tannerite inside the trung of his car at the parking lot here at the mandalay bay. so what was he planning on doing? was he planning on blowing up that car? using it as part of an escape plan or was he planning on carrying out an attack? -- another attack, i should say. the under sheriff said today that all he knows is that it was part of what he called the shooter's nefarious intent. >> that under sheriff also had more information today about the security guard at the mandalay bay, who was the first one to come across the shooter he. this man sounds like he saved a lot of lives. >> he did. the under sheriff wanted to make sure that we awe know his name,