Story highlights Investigators found "survival gear" in Stephen Paddock's hotel room, including bulletproof vests, sources say

"Incendiary" rounds were recovered near a 43,000-barrel fuel tank investigators say the gunman fired at, sources say

(CNN) Las Vegas gunman Stephen Paddock fired special "incendiary" bullets at a 43,000-barrel fuel tank in what investigators believe was an attempt to cause an explosion, two law enforcement sources told CNN.

Those types of rounds, meant to ignite what they hit, were found inside Paddock's room at the Mandalay Bay Resort and Casino and near the fuel tank a short distance away on the grounds of McCarran International Airport, the sources said.

Authorities have previously disclosed that Paddock fired at the tank and struck it with two rifle rounds, when he opened fire on the crowd below from his 32nd floor hotel room on October 1. They had not disclosed that he used incendiary rounds to fire at the tank, which contains jet fuel.

The sources, briefed on the investigation but not authorized to speak publicly, said the incendiary rounds were recovered in an area near the tank.

It is unclear if the rounds that struck the tank were also of the incendiary variety. Chris Jones, an airport spokesman, said he was unaware of any rounds being recovered other than those that struck the tank.

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