They were hiding together in a stall when they heard Mateen's footsteps, she said.
"It's like an indescribable amount of fear. It's petrifying. It was silent for a moment. We just started praying and then you just hear his footsteps come into the bathroom.
"Then he starts firing into the bathroom non-stop. He keeps firing until his gun jams. That's the only thing that stopped him."
When the shooting stopped, Carter, who was in the Florida city on holiday from university in Philadelphia, realised she had been shot in both legs.
Her friends were also shot, and Murray would die from her injuries before help arrived.
At 18, she was the youngest of the 49 victims.
It was three hours before police were able to come to their aid, Carter said.
"It was torturous . . . we had to watch people die. It was horrible."
Even when help came she did not feel the danger was over. That came a few days later in hospital, when she decided it was time to "take a breather and just come to some sense of peace with the whole thing".
Ongoing acts of terror, such as in London and Manchester, meant she still felt unsafe.
"Anything can happen at any time and it's really hard to feel safe any more after something like that."
But she also wanted other survivors not to lose hope.
"Keep going, keep living. Don't be afraid of living. This type of thing can stop you from living completely if you let it, and you just can't.
"You don't know how strong you are until you don't have any other choices."
