The director of Cincinnati Zoo's has insisted the decision to kill a gorilla after a boy entered its enclosure was the right one.
Thane Maynard told a news conference that the four-year-old boy's life was in danger when he strayed into the moat at Gorilla World.
He said the 420lbs gorilla called Harambe was agitated and disoriented and acting erratically. He added the western lowland gorilla was extreme strong and could crush a coconut in its hand.
Read more: Incredible footage shows gorilla shot dead holding child's hand and comforting him
A witness reported hearing the boy tell his mother he wanted to get in the water at the enclosure on Saturday afternoon. She said no, but the boy entered a moat in the gorilla exhibit anyway.
Mr Maynard said the zoo is reviewing security measures to ensure both visitors and animals are safe.
He revealed staff have received messages of support and condolences from around the world after the decision to shoot the gorilla.
He acknowledged there were also critics of the zoo's decision, describing the situation as "very emotional".
"Not everyone shares the same opinion and that's OK," Mr Maynard said. "But we all share the love for animals."
Earlier animal rights activists staged a vigil for Harambe at the zoo.
Anthony Seta, of Cincinnati, called the animal's death "a senseless tragedy", but said the purpose of the vigil was not to point fingers but to pay tribute to the gorilla, named Harambe.
"People can shout at the parents and people can shout at the zoo," Mr Seta said. "The fact is that a gorilla that just celebrated his birthday has been killed."
The gorilla's birthday was on May 27, the day before he was shot.
There has been an outpouring on social media of people upset about the killing. A Facebook page called Justice for Harambe has drawn wide attention, along with online petitions and another page calling for a protest at the zoo on June 5.
Videos taken by zoo visitors showed the gorilla at times appeared to be protective of the boy, but he also dragged him through the shallow moat.
The boy was taken to Cincinnati Children's Hospital Medical Centre for treatment and was released on Saturday night. His parents said in a statement on Sunday that he was "doing just fine".
Many social media commenters have criticised the parents and said they should be held accountable.
Villanueva, a 28-year-old mother-of two, said: "I do think there's a degree of responsibility they have to be held to. You have to be watching your children at all times."
A Cincinnati police spokesman said there are no charges being considered. A spokeswoman for the family said they have no plans to make additional comments.
The People for the Ethical Treatment of Animals released a statement from its primatologist Julia Gallucci saying the zoo should have had better barriers between humans and gorillas.
"This tragedy is exactly why Peta urges families to stay away from any facility that displays animals as sideshows for humans to gawk at," the statement said.
The zoo said it is the first such spectator breach at Gorilla World since it opened in 1978 and that the exhibit undergoes regular outside inspections. The zoo said earlier this year it plans to expand the exhibit.
Gorilla World remained closed on Monday.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article