PARIS -- Experts at a zoo in the Moroccan capital of Rabat are trying to understand why an elephant hurled a stone toward visitors, killing a 7-year-old girl.

The behaviour of the female elephant was "abnormal" and needs to be understood, a veterinarian at the zoo said Friday.

The girl was visiting the Zoological Garden of Rabat with her family on Tuesday, admiring three elephants when one picked up a stone, then tossed it more than 10 metres (yards) over a huge ditch and a wooden barrier toward the visitors. The girl was struck in the head and died hours later.

The elephant exhibit has been temporarily closed, zoo veterinarian Abderahim Salhi said by telephone. He said that zoo personnel remained in shock three days later at what he called an "unforeseeable accident."

"The behaviour ... of any animal is very complex," he said, "and wild animals are unpredictable."

"We are all surprised. We don't yet understand," Salhi said.

The zoo, which opened in 2012 on the edge of Rabat, was designed to show animals living in replicas of their natural habitat -- but with no direct contact with visitors, Salhi said. Stones are plentiful inside the elephant habitat, as they would be in their natural surroundings.

"We are very sad at what happened, but it would be wrong to blame the elephant. This was not premeditated," said Salma Slimani, in charge of zoo administration.

Zoos elsewhere have been faced with tragedy when animals injured or killed their human admirers.

In May, a gorilla at the Cincinnati Zoo in Ohio dragged a 3-year-old boy who had climbed over a protective barrier and fell into a shallow moat. A response team shot and killed the 17-year-old gorilla to protect the child.

In June, a 2-year-old boy was killed by an alligator which snatched him as he waded in a lake at a hotel of Walt Disney World Resort in Orlando, Florida. However, the alligator was not part of an exhibit.