A 17-year-old schoolboy was killed by a white tiger, allegedly after he fell into the enclosure of the animal, at a Delhi zoo on Tuesday. Here's a look at other animal attacks in zoos across the world.

1994: A 29-year-old Australian tourist climbed a fence to get close-up pictures of a polar bear at the Anchorage Zoo, Alaska. She was mauled but survived the attack.
2007: A 350-pound Siberian tiger managed to escape its cage in a San Francisco Zoo. It mauled three men, killing one. Authorities were unsure of how the tiger escaped, but it was clear that the animal somehow travelled over a 20-foot wall and a 15-foot moat.
2007: A man trying to take a close-up mobile phone photo of a Royal Bengal tiger at a zoo in Guwahati was mauled to death. The 50-year-old father of two jumped over a protective barricade and was attacked by the tiger.
2008: Three white Bengal tigers at the Singapore Zoo mauled a 32-year-old zoo cleaner to death after the man walked through a moat surrounding their enclosure.
2009: A woman jumped a fence at the Berlin Zoo, entering the polar bear enclosure during feeding time. She was pulled out after a bear attacked her and treated for severe injuries.2011: A 21-year-old man was killed after he entered the Siberian tiger den at the Copenhagen Zoo, in Denmark. It was the first such incident in the 152-year history of the zoo.
2009: A woman jumped a fence at the Berlin Zoo, entering the polar bear enclosure during feeding time. She was pulled out after a bear attacked her and treated for severe injuries.2011: A 21-year-old man was killed after he entered the Siberian tiger den at the Copenhagen Zoo, in Denmark. It was the first such incident in the 152-year history of the zoo.
In this television frame grab from an Indian news channel, a white tiger mauls an Indian schoolboy at the Delhi Zoo in New Delhi. (Agencies)