Dr David Agus, from the University of Southern Caifornia, told CBS News: “I can only imagine the post-traumatic stress associated with what was going on here.
“This is being at war, and these people at this concert were at war.
“There will be all sorts of significant manifestations. That’s something that obviously after the event the medical community will start to set up ways to deal with these individuals and figure out how to help them as much as possible.”
But Dr Agus warned that: “Right now the focus is only on one thing and that is saving lives.”
Stephen Paddock slaughtered at least 50 victims and injured more than 400 more after unleashing a machine-gun rampage on the Route 91 country music festival.
Paddock positioned himself on the 32nd floor of the Mandalay Bay hotel and casino across the world-famous Las Vegas Strip.
The 64-year-old murderer fired a hail of bullets towards the music festival, gunning down innocent victims enjoying Jason Aldean playing the final song of his set.
Some 22,000 people were in the crowd when Paddock opened fire, sparking a panic in which some people trampled on others, as law enforcement officers scrambled to locate the gunman.
Stephen Craig Paddock was a resident of Mesquite, Nevada, with no known terror connections. He was found in the room dead, having spent much of the weekend there, police say.
The Nevada native is believed to be a grandfather who lived with Marilou Danley in Babbling Brook Court.
Records show Paddock lived in a three-year-old, £297,554 ($396,000) two-bedroom home in the tiny desert community of Mesquite.
The incident has been confirmed as the deadliest mass shooting in US history, surpassing the Orlando shooting at the Pulse nightclub in June 2016 when 49 people were killed.
Updating reporters on the incident, Joseph Lombardo, the sheriff of the Las Vegas Metropolitan police department, said: “We are looking at in excess of 50 individuals dead and over 200 individuals injured … Obviously, this is a tragic incident and one that we have never experienced in this valley. My condolences go out to the loved ones.
Authorities “located numerous firearms” in Paddock’s hotel room as investigations into the incident continue.
Lombardo said: “It is going to be a long and tedious investigation. We are bringing in all the resources of the FBI to assist us in this investigation, in particular to their victim witness advocates and their CSI folks to help us process the scene and ensure that we are getting all the evidence that we can possibly obtain.”
Police have also said that Marilou Danley, a woman who is thought to have been his roommate, is no longer believed to have been involved in the shooting.