Las Vegas gunman Stephen Paddock fired "incendiary" bullets in an unsuccessful attempt to explode a tank of jet fuel in his attack on concertgoers at a country music festival, CNN reported Tuesday, citing two law enforcement officials.

Paddock, 64, fired the special ammunition — meant to ignite upon contact — at a 43,000-barrel fuel tank at the McCarran International Airport near the festival, the sources told CNN.

The rounds were reportedly recovered in Paddock's room at the Mandalay Bay Resort and Casino, where he fired on the crowd, as well as near the tank on airport grounds a short distance away.

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Airport officials have said that two rounds hit a tank of jet fuel, while one round penetrated it. But officials did not disclose that he had used incendiary rounds when firing at the tank.

CNN noted that it was unclear if the rounds that actually struck the tank were of the incendiary variety, adding that an airport spokesman said he was unaware of any other rounds being recovered besides the ones that hit the tank.

Officials last week downplayed the possibility of any explosion triggered by gunfire, given designs meant to withstand brief exposure to flame.

Investigators also found "tracer" rounds in the hotel, which are used to illuminate the path of the bullet and improve accuracy in low visibility, CNN reported.

Paddock was found dead in the hotel room, and a total of 47 firearms and thousands of rounds of ammunition were recovered in his suite and two homes. 

Paddock reportedly first fired at the jet fuel tanks before opening fire into the crowd of attendees at the concert on Oct. 1, killing 58 people and wounding more than 500 in the deadliest mass shooting in modern U.S. history.