Leishman said the Occupational Safety and Health Administration has begun investigating the incident as a workplace accident and had been on the site twice since Sunday to interview other zookeepers. The park's safety policies are also being reviewed.
"We feel very confident in those [safety] procedures," Leishman said.
Meanwhile, the injured zookeeper is recovering from her injuries. Leishman said she is "doing well" and would be back to work soon.
"This was unfortunately a freak accident," he said.
The park's Wild Kingdom Train ride takes visitors around the park to see its collection of exotic and native animals.
An inventory of the zoo's animals from a June inspection by the U.S. Department of Agriculture lists 50 animals, including five American bison, six elk, 11 fallow deer, three kangaroos, two lions and six tigers.
The train ride has attracted controversy, however, as animal-rights groups have decried what they call inhumane treatment of the animals. In 2012, the Utah Animal Rights Coalition organized about 30 protesters who said the park put its animals in cages that were too small and called for the zoo to be shut down so the animals could be relocated to sanctuaries.
Leishman said the zoo's record with the USDA, which oversees and inspects the zoo regularly, is "very good," and called the ongoing accusations against Lagoon "hollow."
Leishman said he was confident that the incident on Sunday had nothing to do with any animal's condition.
"The treatment of our animals is superb," he said.
The last time the USDA found a violation at Lagoon was in 2011. An inspection report from September 2011 states that the park committed an "indirect violation" by not continuing to test its leopards after they had previously been found to have intestinal worms known as ascarids.
"The leopards were treated immediately, but no subsequent fecal tests have been performed to ensure that the ascarids were successfully eradicated," according to the USDA report. Follow-up investigations as of June this year revealed no further violations.
A 2006 violation provided to The Salt Lake Tribune in 2012 by animal-rights activists also reprimanded the park for not providing "timely and accurate information" to a veterinarian on a health problem that led to the euthanasia of a kangaroo in June 2006.