Outrage sparked across the world when a famous research lion named Cecil was killed by Minnesota dentist Walter James Palmer.

Cecil lived in Hwange National Park and was being used for a large lion study by Oxford University.

“I had no idea that the lion I took was a known, local favorite, was collared and part of a study until the end of the hunt,” Walter Palmer said to CBS News. “I deeply regret that my pursuit of an activity I love and practice responsibly and legally resulted in the taking of this lion.”

On Twitter, an outrage sparked causing 672,000 tweets about Cecil. Model Cara Delevingne tweeted,

“ This #WalterPalmer is a poor excuse for a human being.”

Palmer worked at a dental office he owned, River Bluff Dental. It is closed right now for Palmer’s safety. Many people have been leaving pictures of Cecil, flowers and stuffed animals in Cecil’s honor.

In the wake of this famous lion’s death, the United Nations Assembly had passed a vote for all countries around the world to be more harsh on people who do illegal wildlife hunting.