As she lay bleeding on the floor, she said the gunman, who remains at large, refused to let her co-workers call 911 to get her medical assistance.
"I said, 'Please help me! He shot me, he shot me! My babies!' He didn't let anybody do anything because he was more worried about taking the money," Shuffield said during a news conference at Methodist Hospital in Indianapolis.
Two days after the shooting, Shuffield, who was five months pregnant, lost her twin girls. She remains hospitalized with an infection created by the bullet that passed through her abdomen.
Her husband, Jason, pushed her in a wheelchair Saturday to a media room where she spent 20 minutes recounting her ordeal and the heartbreak of losing their twins after a pregnancy that had recently become easier after a difficult first three months.
Katherin Shuffield said that she started working at the bank branch in March 2007 and that since then it had been robbed three times, including the April 22 holdup.
Both she and her husband strongly criticized the level of security at the branch, saying it was insufficient to protect the staff from the threat of violence during a robbery.
"You never get the security you deserve," she said.
Messages seeking comment were left Saturday at Columbus, Ohio-based Huntington Bancshares.
Shuffield said she didn't realize she had been shot during the holdup until she felt blood on her leg as she lay on the floor.
Life seemed to be moving in "slow motion," she said, but she was aware enough of her dire situation to ask a co-worker to hand her cell phone to her. She used it to call her husband at his job at Lockheed Martin Corp. to tell him she had been shot.
Jason Shuffield said he and his wife of more than five years are still coming to grips with the shooting.
"We're just trying to hang in there and take everything day by day," he said quietly.
Katherin Shuffield, who had been five months pregnant, said that a nurse showed she and Jason photos of their twins, and that each fetus could have fit in the palm of her hand.
"When I see the pictures with my husband we always try to be strong and don't cry. But it's hard to see that they were so little," she said, her voice cracking.
Indiana law allows prosecutors to charge people with murder in cases where a fetus dies, but only if the mother is at least seven months pregnant.
Because Shuffield was five months pregnant, officials can pursue charges only of feticide, which carries a lesser sentence of two to eight years in prison. The maximum prison time for murder is 65 years under state law.
The couple said they are confident police will eventually catch the gunman. Sgt. Matthew Mount of the Indianapolis police said Saturday that several detectives are continuing to investigate.
"They're following leads and they'll keep on working until we find this guy," he said.