Two zookeepers were injured during an attack by a jaguar at Al Ain Zoo.
The men, who are believed to have discharged a fire extinguisher to scare off the big cat, were taken to hospital with injuries, according to media reports.
“We are investigating the incident to determine its causes and make the necessary recommendations," Ghanem Mubarak Al Hajeri, director general of Al Ain Zoo said in a statement.
The accident happened on Sunday but only came to light on Wednesday.
The cage door was unintentionally left open, according to the local newspaper Gulf Today.
Officials said no members of the public were at risk at any time.
The men are not thought to be seriously injured. One has already been released from hospital and the other is expected to be able to go home on Thursday.
Al Ain Zoo is located at the foot of Jebel Hafeet mountain and is a popular attraction with schools and visitors.