(CBS News) Psychiatrists say victims and witnesses of the shooting tragedy at a Colorado theater are likely to experience a stress reaction in the immediate aftermath of the event, but people with a past history of mental illness or a traumatic event face additional risks.
The violent scene at a Century 16 theater at the Aurora Mall unfolded around 12:30 a.m. local time when a gunman, identified by police as 24-year-old James Holmes, reportedly entered through an emergency exit door and threw two devices that gave off an irritant before opening fire. Twelve people have been killed and dozens more were injured.
"All the witnesses to this horror will be faced with the reliving of this event," says Dr. Victor Fornari, director of child/adolescent psychiatry at North Shore-LIJ Health System in New Hyde Park, N.Y.
He told HealthPop that they may experience anxiety, difficulty sleeping or a heightened startle response, such as if someone opens a door and they jump. This reaction in the aftermath of trauma are called an acute stress reaction.
However, members of the crowd who have experienced a prior traumatic event, such as in military service, may face additional mental health risks, Fornari said.
"One way the mind works, when someone experiences a traumatic event, if they've had earlier traumas, they're bought back," he said.
This can be true even for people who weren't direct witnesses of the shooting but are watching news coverage. An example he used was following 9/11, Holocaust survivors he treated in a Long Island were suddenly afraid of taking a train over safety fears, "rekindling earlier traumas."
He notes the distance between Aurora, Colo. and the site of the 1999 Columbine High School shooting in Littleton, Colo. may bring back past trauma and heightened symptoms for many. The two towns are about 15 miles apart.
"I'd imagine the entire community is reverberating with another tragic sense of this shooting, reliving all these horrors from years ago," he said.
Dr. Alan Manevitz, clinical psychiatrist at Lenox Hill Hospital in N.Y., told HealthPop that the location of the shootings, a movie theater - which has traditionally been considered a safe location - may upend reality for many people. Some may fear going to see the movie, wondering whether it's a one-off incident or there's potential for copycats.
"The only thing you think will go bad [in a movie] is to have a fire and go through the exit door," he said, "and here all the fear comes through the exit, totally turning everything upside."
He referenced New York City Police Department announcing there will be increased security at theaters playing "The Dark Knight Rises" as one such example of reassuring the public's safety.
Given the movie's PG-13 rating, some witnesses of the tragedy may have been children and adolescents, who may display different symptoms of stress than adults.
Manevitz said parents should look out for if their kids are ruminating a lot about the shootings, fixating on their own vulnerabilities or are showing changes in behavior such as separation anxiety or a new onset of fears (such as of the dark). Use that as an opportunity to watch the news with them and discuss the shootings, answering their questions and providing support, Manevitz said.
In addition to prior trauma, witnesses with a history of an anxiety disorder or substance abuse may be more vulnerable to experiencing more severe, potentially longer-lasting effects. Symptoms may include frequently reliving the event, numbness and avoidance of activities, places or people. Children and adolescents may especially be more likely to have aggressive, frightening dreams.
Both psychiatrists say such symptoms should be a flag for loved ones to turn to crisis intervention to get professional help.
"It's very important that you monitor yourself and you're eating right, getting some sleep," said Manevitz. "If you find yourself having any of those symptoms affecting your mood or ability to do your job, you'd certainly need some help."
If people are still experiencing symptoms an acute stress reaction after a month, they may have a more serious problem like post-traumatic stress disorder (PTSD).
The good news, Fornari said, is most people who don't have these prior traumas or mental health conditions have good adaptive coping mechanisms that will allow them to deal with these unspeakable experiences and restore their sense of well-being over time, even if they are startled and anxious during the acute phase of stress.
For the others who may be more symptomatic because of their mental health history, he said there are effective trauma-specific treatments, such as cognitive behavioral therapy, that have been shown effective following high-profile traumatic events such as the Oklahoma City bombing or 9/11. However he does not recommend intervention with a psychiatrist or psychologist for all witnesses of the tragedy.
"In the past there was this sense that debriefing was for everyone," Fornari said. "We've realized more people have coping strategies, so we should only intervene in people who's natural coping mechanisms are not helping them."