Thirteen people have been killed and 30 injured in a shooting at the Fort Hood military base in Texas, in an act described by President Barack Obama as "a horrific outburst of violence".
People who were at the base, or who had loved ones there, have told the BBC of their fear and despair in the moments after the attack.
Fort Hood was sealed off after the attack.
"We are saddened here and upset, and we want to go home," said a serviceman who was caught in the lockdown and who asked not be named.
He said the shooting came just before the base shut for the day at 1500 local time - Thursday being the shortest working day in the week.
"It's arranged this way so that we soldiers can spend quality time with our families," he said. "This is so terrible and frightening."
Carol, the wife of one serviceman who works at the base said she "felt sick with worry for almost an hour" as she tried in vain to reach her husband by phone.
"I can't tell you what was going through my head. I was just praying he would be okay," she said from her home in San Antonio.
"After 45 minutes of feeling so much distress, he called me. All he could say was 'I'm okay' and he put the phone down. I'm so relieved," she added.
Another woman, Elizabeth, lives three blocks from the base where her husband works.
She told the BBC: "My husband came home and got his assault pack. He's on the immediate response team so he was called to get to the base as quickly as possible."
"He's clearing up now and policing the area. I can't talk to him or get hold of him.
"I heard sirens going off. I heard announcements going off - possibly for the lockdown. The sirens are mounted on poles so they are really loud."
Alex, a student, said his school was placed under a "soft lockdown" for about 40 minutes.
He said teachers were instructed to lock the classroom doors, close the blinds, and keep students away from the windows.
"The students in my class were scared until we learned about the situation via the internet," he said.
"When we learnt about what was going on, I calmed down. I feel much safer now."
Local resident Wendy Park said her reaction was one of disbelief.
"I can't believe somebody would do this," she said.
"I mean, so much has happened in Fort Hood since the war started, it's hard to believe one of our own could do something like this."
But another woman, Carla Niswonger, saw the shooting as linked to the US military's operations in Iraq and Afghanistan.
"[I'm] very humbled, but yet not thoroughly surprised because of this being the largest military installation in the free world," she said.
"You know, we have a lot of people with a lot of problems from serving in Iraq, Afghanistan, Vietnam - as my husband did - and it's just hard to control our emotions sometimes."
Sharon Gregory, 48, who lives just a few roads away from Fort Worth said the community had long feared an attack.
"I kind of thought after 9/11, it was only a matter of time before there was a terrorist attack here. I almost wish it had been," she told the Texas Statesman newspaper.