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.