One day after he fled the massacre at Orlando’s Pulse nightclub, Josean Garcia kept hearing gunshots.

Eight weeks after a man crashed his pickup truck into a Texas restaurant and fatally shot nearly two dozen people, survivors told researchers they couldn’t dine out without scanning eateries for armed assailants.

And nine years after a gunman killed 32 people on the Virginia Tech campus, Colin Goddard still inspects each room for escape routes.

“Where are the doors?” he said, explaining his typical thought process. “Is that window something I could break with a chair?”

The memory of a mass shooting can haunt survivors for years. Everyone’s story is different: Some lost loved ones. Some watched them die. Some were gravely injured. Others walked away with no physical scars.

After decades of high-profile attacks, psychiatrists say they can better predict how such violence will affect the people who live through it in the fresh aftermath and over stretches of time. Survivors grieve intensely, they've found, but aren’t likely to develop a psychiatric illness. Those who do most commonly suffer from post-traumatic stress disorder, which carries a bundle of life-choking symptoms.

Goddard was one of 17 students in Norris Hall’s Room 211 when 23-year-old Seung-Hui Cho barged inside and walked through the aisles methodically shooting. Goddard hid under a desk, called 911 and felt a bullet hit his ankle, then his leg, then his shoulder.

His teacher and 11 classmates died.

“I’ve dreamt about that morning happening a billion different ways,” he said. “From me saving the day, to me getting killed. You're going to relive that moment. At some point, you have to realize, you’re going to drive yourself crazy.”

Goddard, now a senior policy advocate at Everytown for Gun Safety in D.C., said he’s grateful to be alive and thinks every day of those who died. He made a full physical recovery and plays on a soccer team. He’s gone skydiving.

But the mental recovery has taken much longer. An outpouring of support from friends and strangers, which began during his six-day hospital stay in 2007, helped his mind heal. Talking about each detail, again and again, helped him process what happened. Still, when he returned to class that year to finish his senior year at Virginia Tech, months passed before he stopped jumping every time someone slammed a door.

Nearly a decade later, Goddard can’t shake certain traits he picked up after the rampage. His defenses are rarely completely down, so it’s difficult to stay truly present in social outings. He’s always looking for the quickest way out of an office, a theater, a bar. A shooting scene in a movie breaks his relaxation. Daily headlines deliver emotional blows.

“Even just hearing about a single homicide in some place it's just like a dart,” Goddard said. “You know that it might not be the world changing thing that's covered by the media every day. But it’s world changing for the family that just lost somebody.”

The Orlando attack early Sunday was the deadliest mass shooting in U.S. history, surpassing Virginia Tech's toll. Omar Mateen, 29, killed 49 people and injured 53 others in a popular gay club. The tragedy struck six months after a married couple killed 14 people and injured 22 others at the Inland Regional Center in San Bernardino, Calif., and eight months after a man killed 10 and injured nine at Umpqua Community College in Roseburg, Ore.

Carol North, director of the Division of Trauma and Disaster at the University of Texas Southwestern Medical Center, said Americans are horrified but no longer surprised by mass shootings. Preventing them should be the policy priority, she said, but helping survivors recover is another important part of the discussion. 

For a 2002 study, North examined the mindsets of people who survived the 1991 massacre in Killeen, Tex. George Hennard, 35, crashed his pickup truck into Luby’s Cafeteria, pumped bullets into the lunchtime crowd, killing 23 and wounding 20, and then committed suicide.

North interviewed 116 people who were in the restaurant when the rampage occurred. Rates of post-traumatic stress disorder were highest, she found, in the first eight weeks after the shooting: 26 percent of respondents exhibited signs of PTSD. The condition causes disturbing images to pop into mind, nightmares, emotional numbness, jumpiness, sleeplessness and trouble with concentration.

A year later, 14 percent of the sample showed these symptoms. Three years later, the share rose to 18 percent, an increase North considers insignificant or a measurement error. (Of the 46 cases of PTSD identified by any of the three assessments, she wrote, 25 were in remission at the three-year mark).

Symptoms tend to soften or disappear in the years that follow, she said. But some deal with the illness for decades.

“I remember being told that when people walked into a restaurant after that, they had to have their back to the wall, facing the door,” she said, “and when anybody came in, their eyes went to the person's hands to check if there's a gun.”

A strong predictor of recovery, she said, is a consistent support system. Survivors with PTSD often need counselors or doctors to prescribe the appropriate medication. More generally, they need people who will check in on them and listen.

Garcia, 26, went to Pulse early Sunday with his two best friends, Amanda Alvear and Mercedez Flores. At some point, he met up with another pal across the dance floor, Bryan Lopez.

Gunshots interrupted their conversation. In an instant, Lopez was on the ground, bleeding. Garcia, shocked to the point of numbness, told him to stay down. What happened next is a blur, he said: He sprinted out a door by the DJ booth, climbed a fence outside and ran to his car. He called a friend to pick him up. His hands shook too hard to drive more than a few blocks.

He hoped Alvear and Flores made it out, too. On Monday, however, he learned they'd died. Lopez was in stable condition at a hospital.

Garcia hasn't slept more than three hours at a time since. He feels both grateful and guilty to be alive. He can't sleep alone. He's worried a gunman will break into his house. He tried to go to work, to get his mind off things, but returned home after a couple hours. His only solace, he said, is sharing memories of Alvear and Flores with friends.

“I keep picturing them helpless,” he said. “I feel physically sick. I keep seeing people on the floor. I keep hearing gunshots.”

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