CHARLOTTE, N.C. – The former assistant director of the FBI’s criminal investigative division says he believes the shooter who killed dozens and injured hundreds on the Las Vegas strip was likely planning the attack for a long time and probably has a military background.

“It’s just extraordinary that one person can inflict that many casualties from a hotel room above an event like that at that distance,” said Chris Swecker.

The suspected shooter, 64-year-old Stephen Paddock, is believed to have opened fire on the crowd of concertgoers from his high-rise hotel room at Mandalay Bay. The room was 32 stories high and perched across the street from the open-air venue.

Swecker believes Paddock turned his hotel room into a “fortress” and likely had multiple fixed shooting locations with at least one fully automatic weapon.

“It had to have been an AR-15, an M-4, or an AK-47 mounted on a tripod, probably in a fixed position on a desk or something,” Swecker speculated. “(He) probably had multiple weapons set up so he didn’t have to reload, he just had to move from one weapon to the next.”

Swecker said he will be interested to find out what authorities learn about Paddock’s profile. He suspects the gunman had military or tactical training and likely prepared for the attack for a long time.

“This person obviously was not on the radar,” Swecker said. “We need to learn as much as we can about the individual.”