(CNN)A keeper at the Palm Beach Zoo died Friday afternoon after being attacked by a rare species of tiger, zoo spokeswoman Naki Carter said. Stacey Konwiser, 38, lead tiger keeper at the zoo, was killed by a 13-year-old male Malayan tiger, one of four at the facility, in the contained area where the animals are fed and sleep, Carter said. Zoo officials said it didn't appear Konwiser did anything out of the norm as she worked in the enclosure, known as the tiger night house, and prepared to talk with zoo visitors about the animals in a "Tiger Talk." The tiger was off-exhibit at the time and no guests could see what happened, Carter said. The tiger was never on the loose, contrary to early reports on social media, she said. West Palm Beach police said the tiger was tranquilized and officers waited until the drugs took effect before they could reach the victim, CNN affiliate WPEC reported. Konwiser was taken by helicopter to St. Mary's Medical Center. Stacey Konwiser with her husband, Jeremy Konwiser. 'A tiger whisperer' Konwiser had worked three years at the zoo and was very experienced with tigers, Carter said. Her husband, Jeremy Konwiser, is also a trainer at the zoo. "This was her specialty," she said. "She loved tigers. You don't get into this business without the love for the animals and understanding the danger that's involved even more." Konwiser had a special bond with the big cats, Carter told the Palm Beach Post. "I kind of referred to her as a tiger whisperer," she said. "They spoke to each other in a language that only they could understand. And I can't put into words or make you understand for anyone who didn't know Stacey how much she loved these tigers and how much this zoo family loved her. And while she's no longer with us, her memory will live on." Konwiser graduated from Mount Holyoke College with a bachelor's degree in biology and received her master's degree in conservation biology from the University of Queensland in Australia, the Palm Beach Zoo's official Facebook page said. OSHA will investigate Stacey Konwiser, 38, was lead keeper at the zoo. Malayan tigers are a critically endangered species. The Palm Beach Zoo provides a special program in which guests can pay extra to see the tigers. There are less than 250 left in the world, Carter said. The zoo is part of a breeding program that aims to keep the animals from becoming extinct. Carter would not comment about the condition of the tiger except to say it has been contained. The investigation is ongoing and the Occupational Safety and Health Administration is taking over. When the attack happened about 2 p.m., guests at the zoo were ushered into the gift shop before being told the zoo was closed for the day. "This is my first time at the zoo," one zoo visitor, Beverly Johnson of Fort Pierce, told the Palm Beach Post. "I wasn't expecting this." The zoo was evacuated and will be closed through Saturday, Carter said.