A mother of two who was shot 12 times when a gunman opened fire in a Cincinnati bank building last month but survived is back at home and has started a nonprofit to reduce gun violence through responsible firearm ownership.

Whitney Austin was released from a hospital on Sept. 11, just five days after gunman Omar Enrique Santa Perez opened fire at the Fifth Third Bank building, killing three people and wounding two others before he was shot dead by police.

"It was a typical Thursday morning," Austin, a Fifth Third Bank vice president who lives in Louisville, Kentucky, said in an interview Wednesday.

Austin told NBC News that as she approached the revolving door to the building in Fountain Square that morning she was on a conference call and, unbeknownst to her, there were already multiple people waving their arms, trying to warn her about the carnage inside.

"One of the frustrations that I have, is that I didn’t put two and two together. I saw a hole in the door, the glass was shattered," she said. She thought it was odd.

"I pushed the door, and immediately that's when I was hit by the bullets," Austin recalled.

"And I remember thinking: 'What? What is this?' I also remember processing immediately that 'Oh, you've been shot," she said. "And it was a burning sensation. It wasn't as painful as I imagined getting shot would be, it was more just shock and this burning feeling over my body."

She was shot mostly in the right side of her body — and in her arm. Austin said she slumped to the bottom of the revolving door and began coughing up blood.

"I just resigned myself to: 'OK, this is it. You're dying. You've been shot, and you're dying,'" she said.

Austin said she prayed as she moved towards her phone to try and call her husband to say goodbye, and the gunman shot her again. She played dead, but when she saw a police officer out of the corner of her eye approaching her feelings of desperation turned to hope.

"I kept shouting at him, 'I have a 5- and a 7-year old. They need their mother. You need to get me out of this situation,'" Austin recalled.

Four officers fired through the building's plate-glass windows to kill Perez and stop the mass shooting, police have said.

A suspected motive in the shooting has not been disclosed, if one is known. Perez, 29, filed lawsuits alleging he was being electronically monitored, which named NBC Universal and CNBC among others. One suit was dismissed by a judge in June and in the other a judge recommended it be dismissed and said the complaint was "rambling, difficult to decipher, and borders on the delusional," according to court records.

Yet police say Perez used a 9 mm handgun that was purchased legally from a local gun store on Aug. 2. He also had a briefcase with around 250 rounds of ammunition, police have said. Perez was not a current or former employee at the bank, and it was similarly unclear why he chose that location, police have said.

Austin has now started a group, called the WhitneyStrong Foundation, which among its goals is to develop proposed legislation so the mentally ill do not have easy access to firearms.

She'd thought about getting more involved in gun violence issues after a gunman killed 17 people at a Parkland, Florida, high school on Valentine’s Day, and signed up for information about meetings and protests, but became distracted by the day-to-day life of working and caring for her kids.

"As I was sitting there, wondering why they weren't saving me, I was getting more and more angry about the fact that I'd ignored all of those messages," Austin said. "I had done absolutely nothing to prevent this exact situation from happening."

She was also in disbelief that she was involved in a mass shooting.

"I think there is a huge group of people, a huge population within the United States, that believes pretty strongly that mentally ill people should not have access to guns," Austin said. "So let's tackle that. Let's figure out how to do that. Because again, we all have the same goals in mind — we want to feel safe. We want our children to feel safe."

"I'm here. I'm alive," she said. "That is now my purpose."

Those killed in the shooting have been identified as Pruthvi Raj Kandepi, 25; Richard Newcomer, 64; and Luis Felipe Calderón, 48.

Austin said that she thinks about those who did not survive. "It's just two totally different outcomes that don't make sense, right?" she said.

"How is it that I — I survived, and thousands of things went right for me, and they didn't, and thousands of things went wrong for them?" Austin said. "It's just, it doesn't make any sense and it makes me upset."