Clark County Sheriff Joe Lombardo said the gunman who killed 58 people at an outdoor concert in Las Vegas last month fired more than 1,100 rounds.
Lombardo shared the new estimate in an interview with the Las Vegas Review-Journal on Wednesday.
The sheriff told the newspaper that he knew of the previously undisclosed number because the Metropolitan Police Department's forensics lab was working closely with the FBI.
Stephen Paddock on Oct. 1 opened fire on a country music festival from a window on the 32nd floor of the Mandalay Bay hotel on the Las Vegas Strip.
Lombardo said police had found around 4,000 more rounds of unused ammo in Paddock's hotel suite, according to the Review-Journal.
The sheriff also told the newspaper he hoped to release more information about the shooting in the next couple of weeks.